ZAGER, Justice.
In this appeal, we are asked to decide whether an employer’s matching contributions to an employee’s 401k plan should be considered part of weekly earnings for purposes of calculating workers’ compensation weekly benefits. We must also decide whether the district court erred in affirming the workers’ compensation commissioner’s decision on the amount of healing, period benefits owed,' the extent of permanent disability, and the penalty to' be awarded. For the reasons stated below, we conclude that , an employer’s matching contributions to an employee’s 401k plan are not weekly earnings for purposes of calculating workers’ compensation weekly benefits. We also conclude the district court did not err in affirming the decision of the commissioner with respect to the extent of permanent' disability. However, we hold that the district court erred in affirming the date when healing period benefits commenced, the date when the healing period benefits ended, and the date when permanent partial disability (PPD) benefits commenced. We therefore affirm in part and reverse in part the judgment of the district court. We remand the case to the district court- with the following instructions on judicial review: (1) to affirm the commissioner’s findings as to the weekly benefit rate and the extent of permanent partial disability and (2) to remand the case to the commissioner for a redeter-mination of the date when healing period benefits commenced in September 2010, for a redetermination of the date when healing period benefits ended and PPD benefits commenced, and for á recalculation of penalty and interest benefits based on the above dates.
I. Background Facts and Proceedings.
David Evenson began working at Winnebago Industries, Inc. in 1987 to supplement his income from farming. On May 18, 2010, while employed at Winnebago, Evenson sustained an. injury to his left elbow. Evenson was an hourly employee at the- time of his injury. On May 27, Even-son sought treatment for pain in his left elbow. He was seen by James McGuire, PA-C. Evenson reported that the pain in his left elbow started after he was stacking aluminum running boards as part of his job duties. Evenson was diagnosed.with left elbow medial epicondylitis. He was provided a brace and advised to avoid lifting running boards until his next appointment. At his next appointment, Evenson reported the pain condition had improved and that he was still working his regular job.- At his follow-up appointment on June 10, Evenson reported that his left elbow was sore because he had been doing extra work at Winnebago and working overtime. Although Evenson had full range of motion in his left arm, McGuire restricted him to working eight-hour days, five days per week.
[363]*363Evenson was also treated by Dr. Carlson. Evenson received a cortisone injection in his left elbow on June 25, and he reported that it reduced his pain significantly. At his follow-up appointment with McGuire, Evenson was told he could continue with his work duties at eight hours per day. At the next appointment, Even-son reported more discomfort with heavy lifting and- gripping, .but also reported that he had been working ten-hour days. On August 17, Evenson reported he was experiencing more pain in his left elbow while working overtime.
On September 3, Evensón receivéd a second cortisone injection from Dr. Carlson. On the same day, he was also given work restrictions, and told not to use his left arm for two weeks. Evenson claims that September 3 is the date when he stopped working, while Winnebago asserts that September 7 is the date that he stopped working. Dr. Carlson made notations on the Winnebago form following the cortisone injection on September 3 that stated:' “OFF 1300 9-3-10 ... can’t accommodate — will give vac. for remainder of day if he chooses or 98 WX — wants Holiday pay so plans to use vac.” Winnebago’s records show that Evenson took one hour of vacation pay on September 3 and that there was a plant shut down on the same day for one-half hour. Evenson was also paid eight hours of holiday pay on September 6 for Labor Day. The records indicate no other vacation pay during the time period between September 3 and September 6.
On September- 7, Evenson had a followup appointment with McGuire. McGuire noted some improvement in the left elbow and advised Evenson to avoid tight gripping and heavy lifting with his left arm. McGuire’s office notations from the appointment- state that Evenson “was told that there is really no light duty in his work area. His supervisor wanted to know if there is some other -alternative to this; otherwise, he will have to be off work.” The notation goes on to say that Evenson “should be off work for another ten days as long as they do not have any light duty for the patient.” (Emphasis added.)
Evenson was eventually referred to Dr, Gibbons, an orthopedic surgeon. On October 5, after his examination of Evenson, Dr. Gibbons gave Evenson work restrictions to only lift up to twenty’ pounds continuously; to push, pull, or lift with his-left arm only 'occasionally; and to avoid repetitive tasks. At a follow-up appointment, Evenson reported that his symptoms were worsening. Dr. Gibbons restricted Evenson to lifting ten pounds continuously and twenty pounds occasionally, and directed him not to púsh/pull or handle/grip with' hi's left arm. Dr. Gibbons lifted these restrictions on January 27, 2011, and Evenson was released to return to his regular duties. Dr. Gibbons reported that Evenson was at maximum medical improvement (MMI) at’ that time. He also noted that he had no impairment rating for Evenson because Evenson retained the full range of motion in his left elbow.
On September 14, 2011, Evenson filed a petitton seeking workers’ compensation benefits related to the injury to his left elbow. Sentry Insurance Company was the workers’ compensation insurer for Winnebago.1
In February 2012, Evenson was again seen by McGuire. At this appointment, [364]*364Evenson complained that he was still having elbow pain and reported numbness and tingling radiating down his arm into the left small and ring fingers. McGuire ordered nerve conduction studies on the left elbow and advised Evenson to limit left hand gripping. The studies showed ulnar neuropathy in Evenson’s left elbow and asymptomatic mild median, neuropathy in Evenson’s left wrist.
Evenson was later treated by Dr; Yanish, another orthopedist. On March 4, Dr. Yanish diagnosed left medial epicondylitis and ulnar nerve impingement. An MRI showed some tendinopathy.'
At the request of his attorney, Evenson obtained an independent medical examination and evaluation (IME), from Dr. Kuhn-lein in March 2012. The IME addressed not only the nature and extent of the injury to Evenson’s left elbow, but also addressed several other body parts and conditions that were separately relevant to his claim against the Second Injury Fund.2
Dr. Yanish performed surgery on Even-son’s left elbow on April 14, after which Evenson underwent physical therapy. Dr. Yanish kept Evenson off work until May 2, but noted that Evenson could not use his left arm upon return to work. On June 10, Evenson reported his pain had improved and he was not experiencing any further numbness or tingling. Dr. Yanish restricted Evenson to not lifting anything over ten pounds with his left arm. In early August, Dr. Yanish changed Evenson’s restrictions to not lifting more than twenty pounds with his left arm. Dr. Yanish also found an improved range of motion in Evensoris left elbow. On August 31, Dr. Yanish changed Evensoris restrictions to only occasionally lifting forty pounds, lifting up to twenty pounds repetitively, and only occasionally lifting up to twenty pounds above shoulder level. On October 7, Dr. Yanish released Evenson from treatment and restricted him to no lifting over twenty pounds and no lifting over his shoulder.
A contested hearing was held on July 6, 2012. Both Dr. Yanish and Dr. Kuhnlein offered opinions. Dr. Yanish allocated a four percent permanent impairment to Ev-enson’s left arm and recommended that Evenson restrict lifting, pushing, and pulling with that arm to twenty pounds. Dr. Kuhnlein rated Evensoris permanent arm impairment at three percent and selected June 7, 2011, as the date when Evenson reached MMI.
Some of Evensoris family members testified — over objection — about their observations of his use of his left-arm after the injury. Evensoris wife testified that he has difficulty with certain tasks and estimated that he lost sixty percent of the use of his left arm. Evensoris father, his father-in-law, and his sister-in-law testified that he has lost some use of his left arm. They estimated, respectively, that Evenson lost sixty percent, eighty percent, or fifty-five percent of the function of his left arm.
Evenson also testified regarding the effect of the loss of use of his left elbow to his home life and hobbiés. Although he continues to farm, he has scaled back his activities significantly and relies on his family’s help. Evenson testified that he is no longer able to steer his farming machinery with his left arm because it is painful and he has trouble gripping the wheel. He,is no longer able to care for his horses. Evenson previously broke his horses to ride, but he is no longer able to do so because he cannot properly grip a rope in his left hand. Evensoris wife is now re[365]*365sponsible for taking care of the horses. Evenson is no longer able to climb ladders on his farm. Due to his left elbow pain, Evenson stated that he is no longer able to ride his snowmobile or his four-wheeler. Evenson testified that the pain in his left elbow is usually at a constant five on a scale of one to ten.
On August 8, 2012, the deputy commissioner issued his arbitration decision. In the decision, the deputy commissioner awarded Evenson fifty weeks of PPD benefits at the rate of $506.42 per week; healing period benefits between April 14, 2011, and June 14, 2011, at the rate of $506.42; and temporary partial disability (TPD) benefits for a number of time periods3 based on an average gross weekly rate of compensation of $763.52. The arbitration decision awarded Evenson only part of the cost of the IME performed by Dr. Kuhn-lein because a substantial portion of the doctor’s evaluation focused on body parts and conditions unrelated to the upper extremity injury claimed by Evenson in this case. The deputy commissioner also concluded the employer contributions to Ev-enson’s 401k plan were a fringe benefit and therefore not included in the calculation of average weekly gross earnings.4 In determining the extent of Evenson’s permanent disability, the deputy commissioner considered not only the impairment ratings determined by the medical testimony, but also the testimony of Evenson’s family members. The deputy commissioner concluded that Evenson suffered a twenty percent permanent loss of use in his left arm as a result of the injury in this case.
The deputy commissioner further concluded Evenson is entitled to healing period benefits. In particular, the deputy commissioner found Winnebago paid all healing period benefits owed up to the time of Evenson’s surgery in September 2011, but found additional healing periods owed for subsequent time off work were both delayed and insufficient in amount. The deputy concluded that Winnebago must pay a penalty because the “defendants failed to provide reasonable cause or excuse for the delay and denial of healing period and temporary partial disability benefits discussed above and certainly did not provide notice of the reason for such delays and denials.”
The deputy stated,
A general award will be made again awaiting more specific calculations of the parties in a manner consistent with this decision. I do not find the use of the weekly rate of compensation of $468.62[5] unreasonable given the considerable fluctuations in claimant’s earnings each week. Also, the amount of the penalties shall be only 25 percent of the amounts delayed or denied as there was no showing of any prior violations of law by Winnebago or Sentry Insurance.
Evenson filed a rehearing application, which was denied. Winnebago and Sentry filed a notice of appeal to the Iowa Workers’ Compensation Commissioner on Sep[366]*366tember 7, 2012, and Evenson filed a notice of cross-appeal. The commissioner issued an appeal decision on August ,2, 2013, affirming the arbitration decision on all issues. Evenson sought judicial review. After a hearing, the district court entered an order on October 14,2014, affirming the decision .of the commissioner. Evenson appealed and we retained the appeal.
II. Standard of Review.
The first issue in this case asks us to engage in statutory interpretation to determine whether an employer’s contribution to an employee’s 401k plan is included in the calculation of weekly benefits. We review the commissioner’s interpretation of Iowa Code chapter 85 for errors at law. Iowa Code § 17A.19(10)(c) (2011); see Iowa Ins. Inst v, Core Grp. of Iowa Ass’n for Justice, 867 N.W.2d 58, 65 (Iowa 2015). We have declined to give deference to the commissioner’s interpretation of various provisions included in chapter 86. Waldinger Corp. v. Mettler, 817 N,W.2d 1, 7 (Iowa 2012) (holding that the commissioner was not -vested with interpretive authority for section 85.34(1)); Neal v. Annett Holdings, Inc., 814 N.W.2d 512, 519 (Iowa 2012) (holding that the 'commissioner' did not have the authority to interpret the phrase “suitable work” under section 85.33(3)); Burton v. Hilltop Care Ctr., 813 N.W.2d 250, 261 (Iowa 2012) (explaining that we substitute- our own interpretation of sections 85.36 and 85.61(3) if we find the interpretation of the commissioner was erroneous); Swiss Colony, Inc, v. Deutmeyer, 789 N.W.2d 129, 133 (Iowa 2010) (explaining that we did not believe the legislature vested the commissioner with the authority to interpret section 85.34(6)).
This’case also asks us to determine whether the district court erred in upholding the commissioner’s findings regarding healing period benefits, the percentage of disability, and the amount of penalty to -be awarded. When we review the commissioner’s findings of fact, we apply the following principles:
The industrial commissioner’s findings have the effect of a jury verdict. We may reverse the commissioner’s findings of fact only if they are unsupported by substantial evidence in the record made before the agency when the record is viewed as a whole. 'Evidence is substantial if a reasonable mind would find it adequate to reach the same conclusion. An agency’s decision does not lack substantial evidence because inconsistent conclusions may be drawn from the same evidence,
Coffey v. Mid Seven Transp. Co., 831 N.W.2d 81, 89’ (Iowa 2013) (quoting 2800 Corp. v. Fernandez, 528 N.W.2d 124, 126 (Iowa 1995) (citations omitted)). Substantial evidence is “evidence that would be deemed sufficient by a neutral, detached, and reasonable person, to establish the fact at' issue when the consequences resulting'from the establishment of that fact are understood to be serious and of great importance.” Iowa Code § 17A.19(10)(/’)(1).
III. Analysis.
A. Employer’s Contribution to Employee’s 401k Account. The parties disagree whether an employer’s matching contributions to an employee’s 401k plan should be included in a weekly rate calculation when determining workers’ compensation benefits. This is an issue’ of first impression for this court. Our determination rests'upon the question of whether matching contributions to a 401k plan are considered “spendable weekly earnings” under Iowa Code section 85.61(9).
Iowa Code section 85.37 provides that the weekly benefit amount paid to an employee is based on eighty percent of the employee’s “weekly spendable earnings.” [367]*367Id. § 85.37. Compensation is based on “the weekly earnings of the injured employee at the time of the injury.” Id. § 85.36, “Weekly- earnings” are defined as “gross salary, wages, or earnings of an employee to which such employee would have been entitled had the employee worked the customary hours for the full pay period in which' the employee was injured.” Id.
“Spendable weekly earnings” are defined as the “amount remaining after payroll taxes are deducted from gross weekly earnings.” Id. § 85.61(9). “Gross earnings” are defined as
recurring payments by employer to the employee for employment, before any authorized or lawfully required deduction or withholding of funds by the employer, excluding irregular bonuses, retroactive pay, overtime, penalty pay, reimbursement of expenses, expense allowances, and the employer’s contribution for welfare benefits.
Id. § 85.61(3).
We must determine whether an employer’s matching contributions to an employee’s 401k plan are considered weekly earnings for purposes of Iowa’s workers’ compensation law. When we are asked to interpret a statute, we turn to well-settled rules of statutory interpretation:
■ The purpose of statutory interpretation is to determine the legislature’s intent. We give words their ordinary and common meaning by considering the context within which they are used, absent a statutory definition or an established meaning in the law. We also consider the legislative history, of a statute, including prior enactments, when ascertaining legislative intent. When we interpret a statute, we assess the statute in its entirety, not just isolated words or phrases. We may not extend, enlarge, or otherwise change the meaning of a statute under the guise of construction.
Bronstad v. State ex rel. Nat. Res. Comm’n, 871 N.W.2d 291, 295 (Iowa 2015) (quoting Schaefer v. Putnam, 841 N.W.2d 68, 75 (Iowa 2013)). ‘We also consider the statute’s ‘subject matter, the object sought to be accomplished, the purpose to be served, underlying policies, remedies provided, and the consequences of the various' interpretations.’ ” Id. - (quoting Cox v. State, 686 N.W.2d 209, 213 (Iowa 2004)).
We first look at the ordinary meaning of certain words contained in the workers’ compensation statutes.. -Section 85.36 defines “weekly earnings” as including “gross salary, wages, or earnings.” Iowa Code § 85.36. “Salary” is defined as the “fixed compensation paid regularly (as by the year, quarter, month, or week) for services.” Salary, Webster’s Third New International Dictionary (unabr. ed.2002). “Wage” is defined as
a pledge or payment of usu. monetary remuneration by an employer esp. for labor or services usu! according to contract and on an hourly, daily, or piecework basis and often including bonuses, commissions, and amounts paid by the employer for insurance, pension, hospitalization, and other benefits.
Wage, Webster’s Third New International Dictionary. “Earnings” are defined as “something (as wages ,or dividends) earned as compensation for labor or the use of capital.” Earnings, Webster’s Third New International Dictionary.
An employer’s contribution to a 401k plan is not dependent upon, the hours an employee works in the normal way we think of the wage or salary an employee earns for working a certain number of hours or days. An employee’s 401k plan is related, at least tangentially, to his or her wage or salary, in that the: amount the employee chooses to- contribute may be based on how much they earn. However, [368]*368an employer’s 401k plan matching contributions are based on an employee’s choice and participation. Ultimately, an employee chooses whether and how much to participate in a 401k plan. After the employee chooses, then the employer matches the contribution to the plan. The portion the employee chooses to contribute certainly comes from his or her normal salary or wage. The added contribution from any match by the employer, however, does not.
It is clear from the ordinary meaning of the words salary, wage, and earnings that an employer’s matching contribution to an employee’s 401k plan is not meant to be included in weekly earnings for purposes of our workers’ compensation statute. When we read the dictionary definitions in conjunction with the exclusionary language contained in our statute, we conclude our legislature intended to exclude employer contributions to 401k plans from the definition of gross earning. See Iowa Code § 85.61(3) (specifically excluding “irregular bonuses, retroactive pay, overtime, penalty pay, reimbursement of expenses, expense allowances, and the employer’s contribution for welfare benefits” from the regular definition of gross earnings).
Evenson contends an employer’s matching contributions to a 401k plan are not welfare benefits, and they therefore should not be excluded from gross earnings under section 85.61(3). We disagree. The ordinary meanings of the terms salary, wage, and earnings inform our interpretation of the term “welfare benefits” in this context. See id. (defining gross earnings as “recurring payments by employer to the employee for employment, before any authorized or lawfully required deduction or withholding of funds by the employer, excluding ... welfare benefits”). A “benefit” is defined as “financial help in time of sickness, old age, or unemployment” and “a cash payment or service provided for under an annuity, pension plan, or insurance policy.” Benefit, Webster’s Third New International Dictionary. “Welfare” is defined as “the state of faring or doing well .,. thriving or successful progress in life ... a state characterized esp. by good fortune, happiness, well-being, or prosperity.” Welfare, Webster’s Third New International Dictionary. The term included in the statute is “welfare benefits,” and the two words should be considered together. Together, welfare benefits can mean something extra given to an employee for their well-being. We conclude a tax-deferred fund often utilized by employees as a substitute for, or in addition to, an established retirement plan clearly falls under the definition of welfare benefits.
The statute contemplates that there may be welfare benefits given to employees that are separate and distinct from their normal weekly earnings. See Iowa Code § 85.61(3). Matching contributions to an employee’s 401k plan fall under this category. As discussed above, we conclude that a 401k plan falls outside the normal definition of wage, salary, or earnings. An employer’s matching contributions to a 401k plan are something extra, in addition to an employee’s normal, earned wages. They provide assistance for employees in planning for retirement. An employer’s contribution to an employee’s retirement account is a benefit (something extra given by an employer) for the welfare of an employee (that employee’s well-being, specifically in regard to prosperity). Thus, under the ordinary meaning of the terms, we conclude an employer’s matching contribution to an employee’s 401k plan is a welfare benefit under the statute.
Further, Iowa Code section 85.61 defines “spendable weekly earnings” as “that amount remaining after payroll taxes are [369]*369deducted from gross weekly earnings.” Iowa Code § 85.61(9). As a deferred compensation plan, an employer’s matching contribution to an employee’s 401k plan is not subject to payroll taxes in a manner that would fall under the statutory definition. An employee who receives a matching contribution to their 401k plan cannot immediately spend the contribution at the time it is paid, unlike a regular weekly wage.
The leading Supreme Court case on fringe benefits is Morrison-Knudsen Construction v. Director, Office of Workers’ Compensation Programs, 461 U.S. 624, 103 S.Ct. 2045, 76 L.Ed.2d 194 (1983). In this case, the Court held that an employer’s contributions to a union trust fund for health and welfare, pensions, and employee training were not considered wages for the purposes of calculating weekly benefits under the District of Columbia’s Workers’ Compensation Act. Id. at 637, 103 S.Ct. at 2052-53, 76 L.Ed.2d at 204. In so deciding, the Supreme Court relied on the fact that the health and welfare, pension, and training funds could not be readily converted to a cash equivalent in the same way as regular wages or the reasonable value of lodging. Id. at 630, 103 S.Ct at 2048-49, 76 L.Ed.2d at 199. The Court also noted that the legislative history indicated that Congress did not intend to include these types of fringe benefits when calculating the rate of compensation benefits. Id. at 632, 103 S.Ct. at 2050, 76 L.Ed.2d at 201.
The majority trend is to treat an employer’s matching contribution to a 401k plan as a welfare benefit that falls under the category of “fringe benefits,” and thus is not included in the calculation of weekly benefits for workers’ compensation purposes. 8 Arthur Larson et. al., Larson’s Workers’ Compensation Law § 93.01[2][b], at 93-20 (rev. ed.2015); cf. City of Lamar v. Koehn, 968 P.2d 164, 167 (Colo.App.1998) (excluding an employer’s contribution to an employee’s pension plan from the calculation of weekly benefits); Luce v. United Techs. Corp., 247 Conn. 126, 717 A.2d 747, 755 (1998) (finding that the calculation of “wages” under the state’s workers’ compensation laws does not include pensions); Rainey v. Mills, 733 S.W.2d 756, 758 (Ky.Ct.App.1987) (declining to find statutory support to include fringe benefits, such as employer pension plan contributions, in weekly wage calculation); Barnett v. Sara Lee Corp., 97 Md.App. 140, 627 A.2d 86, 90-91 (1993) (finding that pension plans could not be considered in the calculation of weekly wages for the purpose of determining a claimant’s industrial loss of use); In re Gagnon, 158 N.H, 391, 965 A.2d 1154, 1159 (2009) (holding that weekly wages are calculated using a claimant’s pre-tax pay and, therefore, it was not unjust for the collective bargaining agreement to exclude employer payments to an employee’s pension plan from the definition of wage); Shaw v. U.S. Airways, Inc., 362 N.C. 457, 665 S.E.2d 449, 463 (2008) (holding that an employer’s contributions to an employee’s retirement account are not included in the calculation of a weekly wage for workers’ compensation purposes); Clopton v. City of Muskogee, 147 P.3d 282, 284-85 (Okla.Civ.App.2006) (relying on Morrisonr-Knudsen in determining that pension plans are not included in the definition of wage for workers’ compensation purposes); Nelson v. SAIF Corp., 78 Or.App. 75, 714 P.2d 631, 631-32 (1986) (finding that pensions are not included in the definition of wages' included in Oregon’s workers’ compensation laws).
We acknowledge that a few states have changed their workers’ compensation statutes to include retirement plans in the definition of fringe benefits. See, e.g., Neb.Rev.Stat. Ann. § 48-1229 (West, Westlaw current through 2016 2d Reg. [370]*370Sess.). Our legislature has not taken such action, and we agree with- the majority trend evidenced by the -eases cited above. An employer’s matching contributions to an employee’s 401k plan fit much more squarely into the fringe-benefits category than that of a regular salary or wage..'» As discussed -earlier, those contributions are hot directly linked to an employee’s salary, nor are they immediately available for the employee to spend in the same way as regular wages. We conclude the commissioner and the district court were correct in. declining to expand the definition of weekly spendable earnings to include employer 401k contributions.
B. District Court Judgment. Even-son also claims that the district court erred by affirming the ’ commissioner’s decision regarding the extent of his scheduled member disability, the commencement dates of healing period benefits, and the amount of penalty awarded. We address each argument, in turn to determine whether the commissioner’s findings of fact, were supported by substantial evidence. See, e.g., Coffey, 831 N.W.2d at 89.
1. Extent of disability. An injury to the elbow, is a scheduled injury (to the- arm) with a maximum benefit period of 250 weeks. Iowa Code § 85.34(2)(ra). The compensation for a scheduled injury, is based on the impairment of bodily function. Westling v. Hormel Foods Corp., 810 N.W.2d 247, 252 (Iowa 2012). “[I]t is a fundamental requirement that the commissioner consider all evidence, both medical and nonmedical. Lay -witness testimony is both relevant and material upon the cause and extent of injury.” Gits Mfg. Co. v. Frank, 855 N.W.2d 195, 199 (Iowa 2014) (quoting Miller v. Lduridsen Foods, Inc., 525 N.W.2d 417, 421 (Iowa 1994)).
In this case, the deputy considered opinions offered by Dr. Yanish, who rated Evenson’s functional impairment at four percent, and Dr. Kuhnlein, who rated Evenson’s functional impairment at three percent. The deputy also heard testimony from various family members about-the injury suffered by Evenson. Based on all of the testimony, the agency found Even-son suffered a twenty percent permanent loss of the use of his left' arm. In making this determination, the agency considered all of the expert medical opinions as well as the testimony of Evenson’s family members. The district court found substantial evidence supporting • the agency’s determination on the extent of Evenson’s disability. On appeal, Evenson contends the commissioner’s disability finding is not supported by substantial evidence and contends he suffered a twenty-one to fifty percent disability in his left arm.
In this -case, the deputy heard and- considered medical opinions, opinions of family members, and the testimony of Evenson himself. In our -review of the. record, we find. substantial evidence supporting the agency's finding on disability and therefore affirm -the district court’s ruling-on judicial review.
> 2. Healing period benefits. Evenson alleges that the commissioner incorrectly determined the commencement dates for healing .period and PPD benefits. The commissioner determined that Evenson had two different compensable healing periods. The first was from September 7, 2010, to September 19, 2010. The second was from April 14, 2011, to June 14, 2011. The arbitration decision awarded Evenson PPD benefits beginning on November 30, 2011., This was based on Dr. Yanish’s impairment rating that placed Evenson at MMI on November 29, 2011. Both the commissioner and the. district court affirmed that commencement date for PPD benefits.
[371]*371Evenson contends-his first healing period began on September 3, rather than September 7. He argues that he first received physical restrictions on September 3 and Winnebago was unable to accommodate his restrictions at that time. Therefore, he was required to be off work beginning on September 3. Dr. Carlson’s progress note reported that Evenson planned to take vacation pay because Winnebago was unable to accommodate his restrictions. McGuire’s progress note for September 7 stated that Evenson should be off work for another ten days, suggesting that Evenson had already been off work before that appointment. Further, Winnebago’s records show that Evenson took one hour of vacation pay on September 3 and that there was a one-half hour plant shut down on the same day. Even-son was also paid eight hours of holiday pay on September 6 for Labor Day. We agree with Evenson that substantial evidence. does not support the commissioner’s finding that the first healing period began on September 7.
Generally, an employer may seek a credit for the good faith overpayment of workers’ compensation benefits. ’ Iowa Code § 85.34(4) — (5); see also 15 James R. Lawyer, Iowa Practice: Workers’ Compensation § 13:10, at 175 (2015) [hereinafter Ioiva Practice ]. Additionally, the commissioner allows credits for sick pay and vacation pay in some situations. Iowa Practice, at 175-76; see also King v. Marion Indep. Cmty. Sch. Dish, Iowa Workers’ Comp. Comm’n, 2013 WL 3185066, at *2-3 (June 10, 2013). If an employee elects to use sick pay or vacation pay during a time in which workers’ compensation benefits are not being paid, an employer is not entitled to a credit for the pay unless the employee later elects to have the vacation or sick pay restored. Iowa Practice, at 176.
Conversely, the commissioner has generally allowed. an employer a credit against healing benefits in the amount of holiday pay paid to an-employee during a healing period. See, e.g., King, 2013 WL 3185066, at ‡2. The rationale for treating vacation and sick pay 'differently than holiday pay is that sick pay and vacation pay are paid leave that an employee accrues over time for previous work that the employee performed. See id. The employee who uses vacation or sick' pay as compensation during a healing period loses the future ability to utilize such benefits for their intended purpose. If an employer is granted a credit for paying an employee for sick or vacation pay that the employee elected to take during a time when the employer should have been paying workers’ compensation benefits, then the cost is shifted to the employee rather than the employer. See id. In contrast, there is not a cost to the employee when they take holiday pay. See id. Holiday pay is not something an employee accrues and can use in 'the future; it is a benefit that is given independent of the employee’s hours worked or choice to take a paid day off. See id. We agree with the approach the commissioner has taken on this issue. If, on remand, the commissioner determines the first healing period began on September 3, then the holiday pay Evenson was paid for September 6 may be credited against Winnebago’s obligation to pay additional healing period.
Evenson also argues that the commissioner should have' awarded PPD benefits beginning on September 20, the. day he returned to work after the first healing period, and then suspended those benefits during his second healing period between April 14, 2011, to June 14, 2011, and recommenced PPD benefits on June 15, 2011.
[372]*372Iowa Code section 85.34 provides the standard for determining when healing period benefits terminate. Iowa Code § 85.34(1). We have recognized that the statute presents a menu of options the fact finder shall consider when deciding that the healing period has ended. See, e.g., Waldinger Corp., 817 N.W.2d at 8-9. Section 85.34 provides that the healing period lasts
until the employee has returned to work or it is medically indicated that significant improvement from the injury is not anticipated or until the employee is medically capable of returning to employment substantially similar to the employment in which the employee was engaged at the time of injury, whichever occurs first.
Iowa Code § 85.34(1) (emphasis added). We have previously recognized that there may be more than one healing period for a single injury. Waldinger Corp., 817 N.W.2d at 8.
“Compensation for permanent partial disability shall begin at the termination of the healing period.... ” Iowa Code § 85.34(2). When there are multiple healing periods, we must determine whether PPD begins to run from the end of the first healing period or whether the fact finder may choose among the multiple healing periods that are supported by substantial evidence, as occurred here. We hold that the statute clearly states the healing period lasts until whichever situation occurs first. Id. § 85.34(1); see also Teel v. McCord, 394 N.W.2d 405, 407 (Iowa 1986). In this case, the first of the three alternative events to occur was Evenson’s return to work in September 2010.
The commissioner found Evenson returned to work on September 20, 2010, after several days off. This ended the first healing period as a matter of law because it was the earliest of the section 85.34(1) alternatives and because PPD “shall begin at the termination of the healing period provided in subsection 1 [of section 85.34].” Iowa Code § 85.34(l)-(2). Because we conclude the first healing period ended on September 20, there is not substantial evidence in the record to support the commissioner’s finding the healing period benefits terminated in November 2011. See Teel, 394 N.W.2d at 406-07 (concluding a claimant’s entitlement to PPD benefits commenced when the claimant first returned to work after his 1974 injury — not after subsequent intermittent healing period or after he finally “returned to work for good” in 1981 after a series of surgeries). The date of Evenson’s first return to work established the end of the healing period and the commencement of PPD benefits because it was the earliest of the three triggering events prescribed in section 85.34(1). Iowa Code § 85.34(1).
Our determination that Evenson’s return to work in September 2010 established the commencement date for PPD benefits is not precluded by the fact that he was entitled to TPD benefits for subsequent weeks when he was medically restricted from working his regular hours. In Presthus v. Barco, Inc., the claimant received healing period benefits after a work-related injury. 531 N.W.2d 476, 480 (Iowa Ct.App.1995). He returned to work, but for approximately three weeks was unable to work regular full-time hours and received TPD benefits. See id. Presthus contended his entitlement to PPD benefits commenced upon his return to work, which was the same time he would begin receiving TPD benefits. Id.6 The commissioner [373]*373held PPD benefits commenced at a later date — after the short period of temporary partial disability. Id, The district court and court of appeals concluded on judicial review that the commissioner correctly delayed the commencement of PPD benefits until the termination of the period of temporary partial disability. Id, at 480-81.
The court of appeals concluded Presthus could not “receive temporary partial and permanent partial benefits for the same injury at the same time” because, it believed he could not be “both temporarily and permanently disabled at • the same time.” Id. at 480.. This language from the Presthus opinion was imprecise and requires clarification. In the world of workers’ compensation, the words “temporary” and “permanent” have different meanings in different contexts. In a medical sense, the court of appeals could have reasoned that Presthus’s injury was not both temporary and permanent in nature at the same time. Yet, the terms “temporary” and “permanent” have different meanings and significance when used in describing the several categories of workers’ compensation benefits employees receive for work-related injuries.
Some categories of compensation authorized under Iowa Code chapter 85 are for the purpose of compensating injured employees during weeks when they experience a temporary total or partial loss of actual earnings (reduced or eliminated paychecks) caused by the injury. See Iowa Code § 85.33(1) (providing for temporary total disability (TTD) benefits for time lost from work for an injury that does not result in a permanent disability); id. § 85.33(2) (providing for TPD benefits during periods when the employee cannot return to work substantially similar to the job performed at the time of the injury, but is able to perform other work consistent with the injury); id. § 85.34(1) (providing for healing period benefits for time lost from work for an injury that results in permanent partial disability). Other categories of workers’ compensation benefits serve distinctly different purposes and are owed when an employee sustains an injury that causes a permanent partial loss of either bodily function (scheduled member injuries • compensated under . section 85.34(2)(a)-(i)), or earning capacity (body-as-a-whole injuries compensated under section 85.34(2)(¾)), or when the employee sustains a permanent total loss of earning capacity under section 85.34(3). Id. § 85.34. So, unlike in the medical world in which an injury is, ultimately either temporary or permanent, in the workers’ compensation world, a.single injury can result in an employer’s liability for both temporary and permanent disability benefits.
As we have noted, the various categories of workers’ compensation benefits have distinct purposes. Thus, because TPD and PPD benefits compensate for completely different categories of losses, an employee who receives TPD and PPD benefits following a single workplace injury is not paid twice, for the same injury or loss. Perhaps in an effort to avoid even the misapprehension that Presthus might be paid more than he was entitled if he simultaneously was owed TPD and PPD benefits for a single work-related injury, the commissioner in Presthus chose to commence the claimant’s entitlement to PPD benefits after a brief period of TPD benefits concluded. Presthus, 531 N.W.2d at 478. The court of appeals affirmed that part of the agency’s decision on appeal, concluding Presthus could not receive temporary and permanent disability payments at the same time for the same injury. Id. [374]*374at 480. We now conclude Presthus was wrongly decided.
In this case, Evenson’s entitlement to PPD benefits commenced when he first returned to work because that is when his entitlement to healing period benefits ended. See Iowa Code § 85.34(1) — (2) (providing healing period benefits are owed “until the employee has returned to work or it is medically indicated that significant improvement from the injury is not anticipated' or' until the employee is medically capable of returning to employment substantially similar to the employment in which the employee was engaged at the time of injury, whichever occurs first,” and stating “[ejompensation for permanent partial disability shall begin at the termination of the healing period” (emphasis added)). Because TPD benefits were paid’ to Evenson after he first re-tened to work following the injury, we conclude the commencement of Winnebago’s obligation to pay PPD benefits cannot be-delayed until after the TPD benefits subsequently terminated under the plain meaning of section 85.34.
Our conclusion that Evenson’s entitlement to PPD benefits was not suspended beyond the end of the first healing period until after his period of temporary partial disability ended poses no risk of duplication or overpayment of benefits under the circumstances presented here. As we have noted, TPD payments are calculated to replace part of Evenson’s loss of actual earnings after he returned to work during' a period of partial disability. The PPD payments, by contrast, ace intended to compensate him for a different loss: a permanent partial loss of his left arm. Thus, although we conclude today that PPD payments can be owed for periods during which a claimant was paid temporary partial disability, no duplication of benefits arises. Our conclusion on this point is also based in part on the fact that the principal purpose of the statutory scheme establishing a date (the termination of the healing period) for the commencement of PPD benefits is the calculation of interest owed on such benefits for the duration of any delay of payment. See, e.g., Teel, 394 N.W.2d at 407 (explaining that interest on PPD benefits was owed from Teel’s first return to work on May 7, 1974 — even though he experienced subsequent intermittent healing periods and the extent of his disability was not known until 1980 — because “the employer in effect [was] holding [Teel’s] money, and presumably earning interest on it”).
We remand for a determination of whether the first healing period began on September 3 or September 7. On remand, the commissioner shall also make a new determination of the date PPD benefits commenced consistent with this opinion;
3. Amount of penalty. Iowa Code section 86.13(4) provides that, if a delay in payment occurs without, reasonable or probable cause or excuse known to the employer, the commissioner shall award a penalty in an amount up to fifty percent of the amount of benefits denied, delayed, or terminated without such reasonable or probable cause or excuse. Iowa Code § 86.13(4)(a). The arbitration award determined that a twenty-five percent penalty was appropriate in this case, stating that
defendants failed to provide reasonable cause or excuse for the delay and denial of healing period and temporary partial disability benefits discussed above and certainly did not provide notice of the reason for such delays and denials. A general award will be made again awaiting more specific calculations of the parties in a manner consistent with this decision. I do not find the use of the [375]*375weekly rate of compensation of $468.62[7] unreasonable given the considerable fluctuations in claimant’s earnings each week. Also, the amount of the penalties shall be only 25 percent of the amounts delayed or denied as there was no showing of any prior violations of law by Winnebago or Sentry Insurance.
The commissioner’s appeal decision adopted the penalty determination, concluding as follows:
The arguments of the parties have been considered and the record of evidence has been reviewed de novo.
Pursuant to Iowa Code sections 86.24 and 17A.15, I affirm and adopt as the final agency decision those portions of the proposed arbitration decision filed on August 21, 2012 that relate to issues properly raised on intra-agency appeal. The calculations of claimant as to healing period benefits, temporary partial disability benefits, princip[al]/interest owed, and penalties assessed are adopted as if fully set forth herein.
The district court considered the penalty imposed by-the commissioner. It considered that Winnebago and Sentry had failed to include interest on some benefits and had failed to show reasonable or probable cause for a delay in paying some benefits. It also considered that the deputy found the weekly rate paid by Winnebago and Sentry prior to the arbitration decision was' not unreasonable based on the impairment rating provided by Dr. Yanish. It noted that Winnebago did not have a history of delayed payments. The district court noted that the penalty amount imposed was half that allowed by the pertinent Code section. The court concluded that this was not a case of extreme denial or delay and held there was substantial evidence in the record to support the twenty-five percent penalty award. We agree with the decision of the district, court that twenty-five percent of the delayed and underpaid benefits is the proper penalty amount. However, because we remand for a recalculation of the healing period and PPD benefits owed, we also remand for a recalculation of the amount of the penalty and interest owed based'on the new healing period and PPD dates.'
IV. Conclusion.
We hold that an employer’s matching contributions to an employee’s -401k plan are not spendable weekly earnings for purposes of calculating weekly workers’ compensation benefits, and we therefore affirm the commissioner’s determination of Even-son’s weekly compensation . rate. We also hold substantial evidence in the record supports the commissioner’s determination of the extent of -Evenson’s work-related disability. We reverse the commissioner’s determination of the commencement date for healing period benefits in September 2010 and his related determination of the commencement date for PPD benefits. We remand this case to the district court with the following instructions: (1) to affirm the commissioner’s findings as to, the weekly benefit rate and the extent of permanent partial disability and (2) to remand the case to the commissioner for a redeter-mination of the date when healing period benefits commenced in September 2010, for a redetermination of the date when healing period benefits ended and PPD benefits commenced, and for a recalculation of penalty and interest benefits based on the .above dates.
AFFIRMED IN PART, REVERSED IN PART, AND REMANDED.
[376]*376All justices concur except MANSFIELD and WATERMAN, JJ., who concur in part and dissent in part.