OPINION
PER CURIAM.
The Director of the Office of Lawyers Professional Responsibility (Director) filed a petition for disciplinary action against respondent Randall D.B. Tigue.. The Director alleged that Tigue negligently and intentionally misappropriated client funds. We appointed a referee, who concluded that Tigue committed the alleged misconduct and recommended an indefinite suspension of at least 2 years. Tigue disputes the referee’s findings of misconduct and recommended discipline. The Director disputes the referee’s recommended discipline, and requests disbarment. We conclude that the referee’s findings that Tigue negligently and intentionally misappropriated client funds are not clearly erroneous. We further conclude that, based on the specific facts of this case, the appropriate discipline for Tigue’s misconduct is an indefinite suspension with the right to petition for reinstatement after 2 years and a permanent prohibition on being an authorized signatory on a client trust account.
[427]*427FACTS
Tigue-was admitted to practice law in the State of Minnesota on October 5,1973.1 We publicly reprimanded Tigue in 2007 for allowing his trust account to become overdrawn, failing, to promptly cure the overdraft, and failing to maintain the required trust-account books and records, In re Tigue, No. A07-1936, Order at 1-2. (Minn. filed Oct. 25, 2007). In 2014, we suspended Tigue for a minimum of 30 days for negligently misappropriating client funds and failing to maintain and retain the required trust account books and records. In re Tigue, 843 N.W.2d 583, 584-85 (Minn. 2014). We conditionally reinstated Tigue on April 28, 2014, and placed him on probation. In re Tigue, 845 N.W.2d 761, 762 (Minn. 2014) (order). Later that year, Ti-gue was admonished for failing to withdraw from representation or otherwise address a' conflict of interest. We revoked Tigue’s reinstatement in April 2015 for failing to file proof that he successfully passed the professional responsibility portion of the state bar examination by the deadline we established in reinstating Ti-gue. In re Tigue, No. A13-0519, Order at 2-3 (Minn. filed Apr. 15, 2015).
Finally, on May 11, 2015, we reinstated Tigue and placed him.on probation until April 28, 2016, subject to the same conditions as were imposed in our April 2014 order. See In re Tigue, 863 N.W.2d 82, 82-83 (Minn. 2015) (order)., The conditions .of Tigue’s probation included that he “shall abide by the Minnesota Rules of Professional Conduct”; “shall maintain law office and trust account books’ and records in compliance .with Minn. R. Prof. Conduct 1.15 and Appendix 1”; and shall make his trust account books and records available to the Director “at such intervals as the Director deems necessary to determine compliance.” Tigue, 845 N.W.2d at 762.
After his reinstatement, Tigue sent his trust-account books and records to the Director on a monthly , basis. In September 2015, the Director instructed Tigue to begin quarterly reporting, and asked him to send his records for October, November, and December 2015 in January 2016. When Tigue provided these trust-account books and records, the Director noted that several shortages had occurred in client trust accounts during that time. The Director issued a notice of investigation and audited Tigüe’s trust account, which led to this petition for disciplinary action.
The Director alleged, and the record demonstrates, that on six occasions between October 2014 and February 2016, Tigue issued payments from his trust account that caused shortages in client-trust accounts.2 The balance of Tigue’s trust account was continuously short of the amount necessary to cover aggregate client balances during the periods from October 10 to November 18, 2014, and October 28, 2015 to January 19, 2016, The overall shortages ranged in amount from $43.55 to $650. Tigue made payments into his trust account to cure- the shortages, and as a result, none of the clients suffered any permanent financial loss during those periods.
Tigue admitted that he caused these shortages by issuing checks without, suffi-[428]*428dent client funds in the trust account to cover them. He testified that, before issuing a check, he determined the balance of funds in a client trust account by comparing'the balance for the previous month’s reconciliation with the carbon copies of checks that he had issued, rather' than referring to an updated version of the client subsidiary ledger. Tigue admitted that he did not reconcile his trust-account books and records for the month of November 2015 until January 2016, despite knowing that he was required to complete monthly reconciliations.
The.Director further alleged that Tigue intentionally misappropriated funds from R.D. R.D. retained Tigue on October 14, 2015, to pursue a matter in federal court. R.D. signed a retainer agreement, which provided for “an advance retainer of $2,000.00, $400 of which will be an advance payment of the U.S. District Court filing fee.” The agreement stated that Tigue would be entitled to “$250 per hour for attorney services” and that, when the retainer funds were exhausted, R.D. would “be billed on a monthly basis.”
R.D. paid Tigue the $2,000 advance retainer in mid-October. Over the next 6 weeks, Tigue disbursed the entire $2,000 to himself. He drafted a complaint and sent it to R.D., but Tigue did not file a complaint in federal court. R.D. testified that he terminated the representation in December 2015. Tigue testified that he was entitled to retain the $400 filing fee as quantum meruit compensation for the services he rendered to R.D. before R.D. terminated the representation.
In August 2016, Tigue sent R.D. a check to refund the $400 filing fee. That check was returned for insufficient funds, costing R.D. a $12 fee. Shortly after the hearing before the referee in September 2016, Ti-gue successfully repaid the $400 with a money order.
After a hearing, the referee found that Tigue negligently misappropriated client funds and failed to promptly cure an overdraft in his trust account, in violation of Minn. R. Prof. Conduct 1.15(a), 3.4(c), and 8.4(d), and the probation conditions imposed in our April 28, 2014 order for reinstatement.3 The referee also found that Tigue intentionally misappropriated a $400 filing fee from R.D., in violation of Minn. R. Prof. Conduct 1.15(c)(4), 1.16(d), 8.4(c), and 8.4(d), and our April 28, 2014 order.4 Finding several aggravating factors and few mitigating factors, the referee recommended that Tigue be suspended indefinitely with the right to apply for reinstatement after 2 years.
ANALYSIS
I.
When, as in this case, “a party orders a transcript of the disciplinary [429]*429hearing, the referee’s findings of fact and conclusions of law are not conclusive.” In re Ulanowski, 800 N.W.2d 785, 793 (Minn. 2011). We do, however, give “ ‘great deference to a referee’s findings and will not reverse those findings unless they are clearly erroneous.’” In re Albrecht, 779 N.W.2d 530, 535 (Minn. 2010) (quoting In re Wentzell, 656 N.W.2d 402, 406 (Minn. 2003)). The referee’s findings are clearly erroneous if they are “without evidentiary support in the record.” In re Jones, 834 N.W.2d 671, 677 (Minn. 2013).
Tigue challenges'the referee’s conclusions that he negligently misappropriated client funds. He' argues that allowing shortages in his trust account was not misconduct because the shortages were caused by mathematical or clerical errors. Tigue contends that he found and corrected his errors by keeping the trust-account records required by the rules of professional conduct and reconciling his accounts as required by those rules.
Misappropriation of client funds occurs when “‘funds belonging to a client are not deposited in a trust account and are used for any purpose other than that specified by the client.’ ” In re Lundeen, 811 N.W.2d 602, 608 (Minn. 2012) (quoting In re Westby, 639 N.W.2d 358, 370 (Minn. 2002)). In this case, Tigue issued checks from his trust account on behalf of a particular client when he did not maintain sufficient amounts from that client in his trust account to cover those disbursements. As a result, funds belonging to other clients were used to cover these cheeks. Although these shortages were typically small and were eventually cured, they are misappropriations because funds belonging to a client were used for purposes other than those specified by the client. See id.
Tigue’s argument that he did not commit misconduct' because he kept all trust-account books and records in the required manner is unavailing. Tigue admitted that he did not keep his client subsidiary ledgers up to date, and the record supports the referee’s finding that this’practice caused Tigue to make mistakes when he calculated the available funds for particular clients. Appendix-1 to the Minnesota Rules of Professional Conduct describes the trust account books and records that attorneys must keep. See Minn. R. Prof. Conduct 1.15(h)-(i). It states: “The following books and records must be contemporaneously maintained.... A subsidiary ledger for each client matter in which the attorney deposits funds into a trust account.”5 Minn. R. Prof. Conduct Appx. 1.1.3 (emphasis added). Appendix 1 also specifies that “[n]o client subsidiary ledger balance should be negative at any time.” Minn. R. Prof. Conduct Appx. 1.1.4 (emphasis added). Tigue’s negligence caused shortages in several client trust accounts, and because he failed to reconcile his trust-account records in December 2015, some shortages lasted for a total of three months. The referee’s finding that Tigue negligently misappropriated client funds is not clearly erroneous.
Tigue argues that he did not intentionally misappropriate the $400 filing fee in the R.D. matter because he was entitled to keep it as payment, under the terms of his retainer agreement with R.D. The retainer states: “Client understands that should it hinder Attorney’s representation [430]*430of Client in any way, Attorney shall immediately withdraw from representation and be entitled to quantum meruit6, compensation as per the terms of this agreement.”
The referee rejected Tigue’s quantum meruit argument .because Tigue’s retention. of the filing fee did, not afford R.D. due process and did not involve any equitable determination of the value that Tigue had conferred on R.D. The Director ar-. gues, also, that the timing is wrong: Tigue disbursed the remainder of R.D.’s funds to himself on November 25, 2015, before R.D. had ended the representation or, Tigue had withdrawn.7
Tigue eites two cases as support for his quantum meruit argument: In re Ganley, 549 N.W.2d 368 (Minn. 1996), and In re French, 864 N.W.2d 183 (Minn. 2015). In Ganley, the attorney kept a $120 filing fee after his client was granted in forma pau-peris status, because he had earned it. 549 N.W.2d at 369. Ganley claimed that the client “knew or should have known” that he would keep -the filing fee if in forma pauperis was granted. Id, at 370. We held that, “[a]t the very-least, Ganley had:a responsibility to explain to his client exactly what would happen to the $120 filing fee if she received IFP status. He never made any attempt to reduce the ‘altered fee structure’ to writing.” Id.
In French, the client wrote a check to “Cover Fees for Appeal,” and the parties disputed whether the payment was- restricted to costs related to the appeal or included attorney fees. 864 N.W.2d at. 185. French retained a cost bond from the court, which the referee found that he was entitled to keep as attorney’s fees for work performed. Id. at 185-86. Observing that the record contained conflicting evidence, we affirmed that decision. Id. at 189-90.
In contrast to Ganley and French, the retainer agreement between Tigue and R.D. clearly reserved $400 for a filing fee, and the quantum meruit provisions did not alter that reservation. Ganley and French dó not support Tigue’s position. And although Tigue may have believed that he was entitled to keep the $400 filing fee under the quantum meruit provisions of his retainer agreement, his testimony to that effect,does not render the referee’s finding clearly erroneous.. See Wentzell, 656 N.W.2d at 405 (“[W]e,give great deference- to a referee’s findings ... especially in cases where the referee’s findings rest on -disputed testimony or in part on respondent’s credibility, demeanor, or sincerity.”). Instead, the record shows that Tigue obtained $400 from R.D. to pay a filing fee; Tigue did not keep these funds in trust; Tigue never paid a filing fee on behalf of R.D.; and Tigue disbursed the $400 to himself. The record supports the referee’s finding that Tigue intentionally misappropriated R.D.’s $400 filing fee.
II.
Having determined that the referee did not err in finding that Tigue committed misconduct, we now consider the appropriate discipline. The parties disagree as to the discipline that we should impose. The Director, disagreeing with, the referee’s [431]*431recommendation to indefinitely suspend Tigue for a minimum of 2 years, requests disbarment. Tigue argues that, if any discipline is appropriate, it-should be limited to a 1-year extension of his probation.
“Although we place great weight on the referee’s recommended discipline, we retain ultimate responsibility for determining the appropriate sanction.” In re Rebeau, 787 N.W.2d 168, 173 (Minn. 2010). “The purpose of disciplinary sanctions is ‘not to punish the attorney but rather-to protect the public, to protect the judicial system, and to deter future misconduct by the disciplined attorney as well as by other attorneys.’” In re Schulte, 869 N.W.2d 674, 677 (Minn. 2016) (quoting Rebeau, 787 N.W.2d at 173).
In determining the appropriate sanction in an attorney discipline matter, wé “consider four factors: (1) the nature of the misconduct; (2) the cumulative weight of the disciplinary violations; (3) the harm to the public; and (4) the harm to the legal profession.” In re Nelson, 733 N.W.2d 458, 463 (Minn. 2007). Additionally, although we look to similar cases to ensure that the discipline imposed is consistent, we “impose discipline on a case-by-case basis after considering both aggravating and mitigating circumstances.” In re Plummer, 725 N.W.2d 96, 99 (Minn. 2006). We address each of the four factors in turn, then analyze the aggravating and mitigating factors in this case, and finally examine similar cases to determine the appropriate sanction for the misconduct committed in this case.
Tigue’s intentional and negligent misappropriation of client funds was serious misconduct. We have held that “misappropriation of client funds [is] a particularly serious violation.” Lundeen, 811 N.W.2d at 608; see In re Tigue, 843 N.W.2d at 587 (stating that even “‘unintentional misappropriation’” warrants severe discipline (citation omitted)). Because misappropriation is such serious misconduct, we “generally disbar attorneys who misappropriate client funds.” In re Wentzel, 711 N.W.2d 516, 520 (Minn. 2006). When, however, the attorney shows substantial mitigating circumstances, we have imposed lengthy suspensions instead. See, eg., In re Rooney, 709 N.W.2d 263, 266, 272 (Minn. 2006) (suspending attorney who misappropriated funds for 18 months after noting numerous mitigating circumstances),
“Whether the presence of mitigating circumstances will allow an attorney to avoid disbarment for misappropriation depends on the severity of. the misconduct and the strength of the mitigating factors.” Id. at 272; see also In re Grzybek, 567 N.W.2d 259, 264 n.1 (Minn. 1997) (stating that while “the misappropriation of small amounts of money is [not] defensible, ... the amount of the misappropriation is an appropriate consideration in determining sanctions”); In re Bernstein, 404 N.W.2d 804, 804-05 (Minn. 1987) (imposing a 4-year suspension on an attorney who misappropriated client funds when the case “involves an isolated instance of misappropriation of a relatively small sum of money, for a short period of time, followed by full restitution” and the attorney “is contrite” and “has shown himself to be a person of good character”).
Having determined that Tigue’s misconduct was serious, we next address the cumulative weight of his violations. Evaluation of this factor' looks- to distinguish those acts representing “‘a brief lapse -in judgment’ ,:or ‘a single isolated incident’ ... from multiple instances .... occurring over a substantial amount of time or involving significant amounts of money.” In re Fairbairn, 802 N.W.2d 734, 743 (Minn. 2011) (citation omitted).
[432]*432Tigue created shortages in six different client trust accounts between October 2014 and February 2016. This repeated occurrence of trust-account shortages suggests that Tigue’s misconduct was not a brief lapse in judgement. On the other hand, the longest period that Tigue’s trust account remained short was about 3 months,- which is a relatively brief period of time. And Tigue’s intentional misappropriation occurred only once, when he retained, the $400 filing fee in the R.D. matter.
Next, we must determine whether, and to what extent, Tigue’s misconduct harmed the public or the legal profession. See Fairbairn, 802 N.W.2d at 743. Tigue’s misappropriation of client funds by its nature harms the public at large and the legal profession, because it betrays the trust the client places in an attorney. See id. In evaluating these factors, we have also considered how many clients were harmed and the extent of the clients’ injuries. In re Coleman, 793 N.W.2d 296, 308 (Minn. 2011). In this case, Tigue’s misappropriation involved relatively small amounts of money. Other than the $12 fee that R.D. was charged when Tigue’s check bounced, no client was permanently deprived of money, although R.D. was denied his $400 for several months before Tigue repaid the funds that he had misappropriated.
Having addressed what harm Tigue’s misconduct has caused to the public and the legal profession, we next determine what aggravating and mitigating factors impact the appropriate sanction. See Fairbairn, 802 N.W.2d at 742, 744. The referee found five aggravating factors.
First, Tigue was subject to prior discipline- in 2007 and in 2014. “[A]fter being disciplined, an attorney is expected to show a ‘renewed commitment’ to ethical behavior.” Coleman, 793 N.W.2d at 308 (quoting In re Milloy, 571 N.W.2d 39, 45-46 (Minn. 1997)). This aggravating factor weighs heavily because the prior discipline was for similar misconduct. See In re Cutting, 671 N.W.2d 173, 175 (Minn. 2003) (holding that similar prior misconduct weighs more heavily in later discipline proceedings for the same attorney).
Second, the referee found as an aggravating factor that Tigue committed misconduct while on probation. See In re Garcia, 792 N.W.2d 434, 443 (Minn. 2010) (holding that committing misconduct while on probation aggravates the misconduct). Third, the referee found that Tigue failed to “recognize that his actions and inactions constitute potential misconduct” and lacked remorse, aggravating his misconduct. See Wentzel, 711 N.W.2d at 522 (citing lack of insight into the nature of the misconduct as an aggravating factor). The record supports these aggravating factors.
Fourth, the referee found that the 10-month delay in returning R.D.’s filing fee and the permanent loss of $12 from the bounced-check fee that R.D. paid aggravated the conduct. While this conclusion is supported by the record, it should not be weighed as an aggravating factor because it duplicates the above consideration of the harm caused to Tigue’s clients. See In re Fru, 829 N.W.2d 379, 390 n.7 (Minn. 2013) (refusing to -consider the attorney’s multiple acts of misconduct over an extended period of time as an aggravating factor because that factor “overlap[ped] with our consideration of the cumulative weight of [the attorney’s] disciplinary violations”).
Finally, the referee' found that Tigue “has substantial experience in the practice of law.” Tigue has practiced law for over 40 years. Committing misconduct despite this substantial experience is an aggravating factor. See Schulte, 869 N.W.2d at 679.
The referee concluded that four factors mitigated Tigue’s misconduct, but that [433]*433they were “not entitled to great weight”: (1) Tigue offered before the present petition to submit his trust-account books and records more frequently than requested by the Director,8 (2) Tigue substantially complied with his probation before the present misconduct occurred; (3) Tigue made substantial but untimely and incomplete restitution to R.D.; and (4) Tigue corrected the trust account shortages for all clients other than R.D. without permanent financial loss to them.
At least two of these mitigating factors, however, are legally improper. “Compliance with the law is no mitigating factor,” In re Grigsby, 764 N.W.2d 54, 61 (Minn. 2009), nor is cbmpliance with' the rules of professional conduct, Albrecht, 779 N.W.2d at 539. As a result, Tigue’s substantial compliance with the terms of his disciplinary probation before committing the current misconduct is not a mitigating factor.
The referee further relied on the lack of harm to clients when he found that Tigue’s payment to R.D. and .the lack of permanent financial loss to Tigue’s other, clients were mitigating factors. We have held that a lack of harm to clients may be considered a mitigating factor. In re Glasser, 831 N.W.2d 644, 649 (Minn. 2013); see Fairbairn, 802 N.W.2d at 747 (determining that when an attorney’s misappropriation of client trust funds does not cause a client to suffer “any prejudice or damage,” the attorney is entitled to mitigation). In a decision filed after oral argument in this case, however, we clarified that lack of harm to clients should not be considered a separate mitigating factor because we have already considered any harm to clients when assessing the harm that the attorney’s misconduct caused the public and the legal profession. See In re Bonner, 896 N.W.2d 98, 110 (Minn. 2017). As a result, although any harm to Tigue’s clients is a relevant consideration when determining the appropriate discipline, lack of harm to clients is not a separate mitigating factor.
Finally, we look to similar cases to-ensure consistency in our disciplinary decisions. In re Nathanson, 812 N.W.2d 70, 80 (Minn. 2012). We recently noted that in “a few instances [we have] imposed discipline less than disbarment in a misappropriation case when the record does not reveal substantial mitigating factors.” In re Matson, 889 N.W.2d 17, 26 (Minn. 2017); see In re Trimble, 822 N.W.2d 291, 291-92 (Minn. 2012) (order) (imposing an indefinite suspension for a minimum of. 2 years on an attorney who misappropriated advance expenses from a client, neglected and failed to communicate with a client, failed to appear in court, and failed to cooperate with the Director’s investigation); In re Brooks, 696 N.W.2d 84, 88-89 (Minn. 2005). For example, in Brooks, we sanctioned an attorney for neglecting 'two clients, failing to maintain trust-account books and records, converting a $200 filing fee to her own use, and failing to cooperate with the disciplinary process. Id. at 86-87. Brooks had been disciplined on five prior occasions, three of which' involved similar misconduct. Id. at 87. Some evidence suggested mitigating factors may have been present, namely that the attorney’s father had died and she was out of state assisting her mother. Id. at 87-88. Noting that Brooks appeared to have abandoned her legal practice entirely, we [434]*434imposed an indefinite suspension with no right to petition for reinstatement for 2 years. Id. at 89.
The referee also cited In re Hanvik, 609 N.W.2d 235 (Minn. 2000). In Hanvik, we indefinitely suspended an attorney with no right to petition for reinstatement for 2 years for misappropriating less than $5,000 in two client matters, making false statements to the Director, clients, and Medicare, failing to respond to a client, failing to maintain trust account records or client ledgers, and providing an incompleté and inaccurate trust-account ledger to the Director. Id. at 236-41. We identified two mitigating factors: Hanvik made restitution of funds to nearly all affected clients and did not have a prior disciplinary history.9 Id, at 239, 241. The referee also concluded that Hanvik’s false statements to an investigator, to the Director, and to Medicare while under investigation were aggravating factors. Id. at 239. Based on these conclusions, , we imposed a 2-year suspension. Id. at 242.
These cases are fair comparisons to Ti-gue’s case. Like Brooks and Trimble, Ti-gue intentionally misappropriated a single filing fee. And like in Brooks, Tigue’s disciplinary history aggravated his misconduct. Brooks and Trimble committed inore types of misconduct than Tigue, however, including neglecting clients and failing to cooperate with the Director. Hanvik is also similar to Tigue’s case. Tigue’s misconduct involved more aggravating factors, especially because Hanvik had no prior discipline, but Tigue’s misconduct was also less serious than Hanvik’s misconduct, which involved misappropriation of more funds, false statements to clients, the Director, and Medicare, and submitting false documents to the Director.
We recognize that misappropriation “ ‘is particularly serious misconduct and usually warrants disbarment absent clear and convincing evidence of substantial mitigating factors.’ ” Garcia, 792 N.W.2d at 443 (quoting In re Rhodes, 740 N.W.2d 574, 579 (Minn. 2007)). Although we have often disbarred attorneys for misappropriating funds because of the critical need for public trust in the legal profession, we do not believe that disbarment is the appropriate discipline here. Balancing the nature and extent of Tigue’s misconduct—which involved a single incident of intentional misappropriation invo|ving a relatively small amount of money, eventual repayment to that client and lack of harm to any other client—and the aggravating factors and the mitigating factors present, we hold that an indefinite suspension with the right to petition for reinstatement after 2 years is the appropriate discipline. We are confident that this lengthy indefinite suspension will adequately protect the public, particularly when combined with the permanent prohibition on Tigue serving as an authorized signer on a client trust account should he be reinstated in the future.
Accordingly, we order that:
1. Respondent Randall D.B. Tigue is indefinitely suspended from the practice of law, effective 14 days from the date of this opinion, with no right to pétition for reinstatement for a period of 2 years.
2. Tigue may petition for reinstatement under Rule 18(a)-(d), Rules on Lawyers Professional Responsibility (RLPR). Reinstatement is conditioned on successful completion of the written examination required for admission to the practice of law [435]*435by the State Board of Law Examiners on the subject of professional responsibility and satisfaction of continuing legal education requirements. See Rule 18(e)-(f), RLPR..
3, Tigue is permanently prohibited from being an authorized signatory on a client trust account.
4. Tigue shall comply with Rule 26, RLPR (requiring notice of suspension to clients, opposing-counsel, and tribunals), and shall pay $900 in costs, áee Rule 24(a), RLPR.