CALABRESI, Circuit Judge:
Decedent, Margot Stewart, gave a 49% share of a mixed-use building to her son Brandon Stewart (“Brandon”). Upon Margot Stewart’s death, the Internal Revenue Service sought to include this gift in Margot Stewart’s estate under 26 U.S.C. § 2036(a)(1), reasoning that Margot Stewart had “retained for [her] life ... the possession or enjoyment of, or the right to the income from the property.” The Tax Court, T.C. Memo 2006-225, 92 T.C.M. (CCH) 357, agreed. Petitioner-Appellant Estate of Margot Stewart (the “Estate”) appeals that decision, arguing that Decedent did not retain a lifetime interest in the 49% share and that there was no implied agreement that Decedent would retain enjoyment of the 49% share. The Commissioner contends that the Tax Court’s decision was correct. We do not disturb the Tax Court’s finding that an implied agreement existed, but we hold that the Tax Court clearly erred in finding [150]*150that the terms of the implied agreement provided that Decedent would retain enjoyment of the entire 49% share, and that the entire property should remain in the Estate. We therefore VACATE the judgment below and REMAND this case for further proceedings consistent with this opinion.
Facts
I.The Two Properties
Since 1989, Decedent Margot Stewart and her adult son Brandon Stewart co-owned, as joint tenants with rights of survivorship, a house in East Hampton, New York (the “East Hampton property”). Each summer, Decedent, and Brandon rented out the East Hampton property, splitting the rental income evenly. As a matter of expediency and convenience, Decedent and Brandon would not both sign the lease; nor would they ask the summer tenant to send two different rent checks, one to Decedent and one to Brandon. Rather, in different years, either Decedent or Brandon would sign the lease to rent out the property, and the tenant would write a single check either to Decedent or to Brandon. Whoever received the rent checks that year would then, every few months, write a check to the other for that person’s ■ share. Decedent and Brandon also split evenly the expenses of maintaining the East Hampton property. The result was that every summer each of Decedent and Brandon received half of the East Hampton property’s net income.
• At all times relevant to this appeal, Decedent and Brandon lived on the first two floors of a five-story brownstone in Manhattan (the “Manhattan property”), which Decedent had bought in 1968. On October I. 1999, Decedent leased the upper three floors to an unrelated commercial tenant, Financial Solutions, Ltd. (“Financial Solutions”). The rent was $9,000 per month, and the term ran through July 31, 2002.
II. The Gift
On October 1, 1999, Decedent and Brandon met with Attorney Frederick Walker, an estate planning specialist, for the purpose of reviewing the Financial Solutions lease. According to Walker’s testimony, Decedent asked him what to do about the appreciation in the value of the Manhattan property, and Walker suggested that Decedent make a gift of part of the Manhattan property to Brandon. Decedent then said that she wanted to give Brandon half of the Manhattan property along with half of the rent. This account is corroborated by Walker’s contemporaneous diary, which says that Decedent wanted “to give son one-half of building and rent.” Walker, Decedent, and Brandon met again the next day so that Decedent and Brandon could pick up the lease and further discuss the gift possibility with Walker.
Decedent was diagnosed with pancreatic cancer in December 1999, and she began chemotherapy treatments in January 2000. On May 9, 2000, Decedent and Brandon signed a deed that transferred a 49% interest in the Manhattan Property to Brandon.1 The deed provided that Decedent and Brandon would be tenants in common.
III. After the Gift
After the gift was completed, Decedent and Brandon continued to live together in [151]*151the lower two floors of the Manhattan property. Financial Solutions continued to rent the upper three floors, but its rent payments were erratic, untimely, and sometimes partial.2 In addition, according to Brandon’s testimony (which is corroborated by financial documentation), the Manhattan property underwent thousands of dollars worth of repairs. As a result, the Manhattan property expenses were significantly higher than usual, at the same time that the income produced by the property became unreliable.
Against this backdrop, the financial relationship between Decedent and Brandon underwent several significant changes during the period after the gift and before Decedent’s death.3 While Decedent continued to receive the Manhattan property rent payments from Financial Solutions, Brandon received the rent payments from the tenant in the East Hampton property. In contrast to their previous practice, Brandon never wrote a check to Decedent for her share of the East Hampton rent. Decedent, who had previously paid for all Manhattan property expenses, now paid for most of them, with Brandon paying a small but not insignificant fraction. The Tax Court found that Decedent paid Manhattan property expenses of $21,790.85, while Brandon paid Manhattan expenses of $1,963. The record supports these findings; every one of these payments is accounted for in Brandon’s and Decedent’s bank statements, and the numbers add up.
IV. Decedent’s Death and Tax Consequences
Margot Stewart died on November 27, 2000. Following her death, the estate filed with the IRS a Form 706, United States Estate (and Generation-Skipping Transfer) Tax Return, which reported the contents of Margot’s estate as including 100% of the East Hampton property4 but only a 51% interest in the Manhattan property. On December 22, 2004, the IRS issued a notice of deficiency stating, inter alia, that Margot had retained possession or enjoyment of the transferred 49% interest and that therefore, under 26 U.S.C. § 2036, the entire Manhattan property was part of her estate for federal tax purposes.
The Estate filed a timely petition in the Tax Court challenging the IRS’s determination of deficiency. The Tax Court held a two-day trial in June 2006. At trial, the Estate argued that, contrary to the IRS’s contention, Decedent had not retained the enjoyment or income of the entire Manhattan property but rather, as a 51% owner, had forgone much of the net income from the top three floors by using a setoff to pay Brandon, and had shared the value of the bottom two by living with Brandon. According to the Estate, instead of split[152]*152ting up the rental income and expenses each month in proportion to their interests in the two properties—a process which would have required Decedent and Brandon to write separate checks for every expense and receive separate checks from both tenants—Decedent and Brandon were keeping track of each person’s net income from both properties and intended to reconcile any differences at the end of the year.
The Tax Court issued a memorandum opinion denying the petition. T.C. Memo 2006-225, 92 T.C.M. (CCH) 357, 2006 WL 3018173, 2006 Tax Ct. Memo LEXIS 230. The court found that Decedent “continued to receive the $9,000 monthly rent payments from Financial Solutions, Ltd., and enjoy the economic benefits of the [Manhattan] property.” Id. at *2, 2006 Tax Ct. Memo LEXIS 230, at *6. The court described Decedent’s “retention of the property’s income stream after the property was transferred” as “very clear evidence that the decedent did indeed retain ‘possession or enjoyment.’ ” Id. Because there was no written agreement between Decedent and Brandon stating that they would reconcile the income and expenses of the two properties and because the Tax Court did not credit Brandon’s testimony that there was an oral agreement, the court found that no such agreement existed. Id. at 2-3, 2006 Tax Ct. Memo LEXIS 230, at *7. Rather, the Tax Court concluded that Brandon and Decedent “had an implied agreement that decedent would retain the economic benefits of the [Manhattan] property” and that “Decedent certainly met the terms of that agreement.” Id. For those reasons the Tax Court held that the full value of the Manhattan property was includible in the Estate under 26 U.S.C. § 2036. The Estate timely appealed to this Court.
Discussion
I. Legal Framework
The Internal Revenue Code imposes a federal tax on “the taxable estate of every decedent who is a citizen or resident of the United States.” 26 U.S.C. § 2001(a). A “taxable estate” is defined as “the value of the gross estate,” less applicable deductions, id. § 2051, where the value of the gross estate includes “the value of all property to the extent of the interest therein of the decedent at the time of his death,” id. § 2033. Some taxpayers use various planning techniques designed to take property out of the gross estate or decrease its value. The IRS has several statutory tools to use in fighting these techniques. One of these tools—26 U.S.C. § 2036(a)(1)—is at issue here.
A. Section 2036(a)(1)
Under Internal Revenue Code § 2036, the value of the gross estate includes “the value of all property to the extent of any interest therein of which the decedent has at any time made a transfer ... under which he has retained for his life ... the possession or enjoyment of, or the right to the income from, the property.” 26 U.S.C. § 2036(a), (a)(1). The purpose of § 2036 is to prevent individuals from using a gift transfer of property with reservation of a life estate—or any similar device—in order to avoid having to pay the estate tax. See Comm’r v. Estate of Church, 335 U.S. 632, 639-42, 69 S.Ct. 322, 93 L.Ed. 288 (1949). Absent § 2036, a decedent could transfer to her heir the remainder in a property while retaining a life estate, and the economic result would be substantially identical to what would have occurred if the decedent had left the property to the heir in her will under an irrevocable contract so to do. By including -such property in the gross estate, § 2036 closes what would otherwise be—and at one time was—an [153]*153enormous loophole in the estate tax.5 Id.
Retention of a formal life estate in a property is just one method a taxpayer might use to try to avoid paying the estate tax while achieving, in substance, the same economic result as would occur if she retained the property for life and only disposed of it by will. Another method is to make an agreement (even an implied or unenforceable agreement) between a decedent and an inter vivos transferee that the decedent will continue to enjoy the benefits of the property for her life. Not surprisingly, the courts and the IRS have ruled that if there is such an agreement, then the decedent is understood to have retained the possession or enjoyment of that property and the property must be included in the gross estate. See 26 C.F.R. § 20.2036—1(c); Estate of Maxwell v. Comm'r, 3 F.3d 591, 593-94 (2d Cir.1993).
In the case before us, the Tax Court found as a fact that when Decedent gave a 49% share of the Manhattan property to Brandon, she did so with an implied agreement that she “would retain the economic benefits” of the whole townhouse. If, as the Tax Court held, Decedent retained the possession or enjoyment of the 49% share of the property that she had given to Brandon, it followed under 26 U.S.C. § 2036(a)(1) that the 49% share was part of the Estate.
B. The Planning Technique in This Case
Today, unlike when § 2036 was enacted, see supra note 5, the estate tax and the gift tax are on a unified rate schedule.6 And, presumably, Decedent owed a gift tax as of the time she transferred the 49% interest in the Manhattan property. See J.A. 334 (noting that the Estate filed a gift tax return for this transfer). Why, then, does it matter whether the Estate pays estate tax or gift tax on the transferred 49% interest? Part of the answer is that the Commissioner wants to tax the appreciation of Brandon’s share of the Manhattan property during the roughly 6-month period from the date of the transfer to the date of Decedent’s death. But the appreciation of the entire Manhattan property during that period was stipulated to be $125,000, J.A. 71, and the tax applicable to Brandon’s 49% share of that appreciation, though not trivial, would probably not be an unduly large amount of money.7
Estate planners have, however, found a highly effective way to lower both estate [154]*154and gift taxes when passing real estate to the next generation. Dividing the real estate into separate interests usually lowers the property’s fair market value and thereby also the taxes due on it.8 See David Westfall et al., Estate Planning Law & Taxation ¶ 2.05[3] (2009). The fair market value of separate interests is typically discounted by about 10-20% for lack of control and marketability. Id. In the instant case, however, the parties stipulated to a much higher discount of 42.5% if the property had in fact been divided.9 J.A. 71-72. That discount is responsible for the lion’s share of the money at stake in this case. It is for this reason that the Commissioner wants us to hold that the entirety of Brandon’s 49% interest is part of Decedent’s gross estate. The Estate would then be taxed as though Decedent, instead of giving Brandon 49% of the Manhattan property on May 9, 2000, had owned the whole property until her death on November 27, 2000. And there then would be no 42.5% discount for lack of control and marketability.
II. Continued Possession or Enjoyment
The Tax Court concluded that Decedent “retained ... the possession or enjoyment of, or the right to the income from, the property.” 26 U.S.C. § 2036(a), (a)(1). “The general characterization of a transaction for tax purposes is a question of law” subject to de novo review. Frank Lyon Co. v. United States, 435 U.S. 561, 581 n. 16, 98 S.Ct. 1291, 55 L.Ed.2d 550 (1978). We must therefore determine what it means, in the context before us, to “retain[ ] ... the possession or enjoyment of, or the right to the income from, the property.”
As an initial matter, we note that two aspects of this statute, as applied to this case, are beyond reasonable dispute. First, Decedent did not retain “the right to income from[] the property.” Retaining the right to income is not the same as retaining the income. As the Supreme Court has explained in interpreting § 2036(a)(2), “[t]he term ‘right,’ certainly when used in a tax statute, must be given its normal and customary meaning. It connotes an ascertainable and legally enforceable power.... ” United States v. Byrum, 408 U.S. 125, 136, 92 S.Ct. 2382, 33 L.Ed.2d 238 (1972). It is undisputed that Decedent did not have a legally enforceable power to receive the income from the interest in the Manhattan property that she had legally transferred to Brandon. Therefore, if Decedent “retained” anything described in § 2036(a)(1), it was [155]*155the actual “possession or enjoyment” of Brandon’s 49% interest, and not any “right to income from” it. Second, “the property” in § 2036(a)(1) here refers to the transferred 49% interest in the Manhattan property, not to the entire Manhattan property. The Tax Court has previously recognized that a decedent’s formal and substantial retention of a majority interest in real property does not necessarily require a finding that the decedent retained possession of a transferred minority interest, see, e.g., Estate of Wineman v. Comm’r, T.C. Memo 2000-193, 79 T.C.M. (CCH) 2189, 2000 WL 839962, at *8-9, 2000 Tax Ct. Memo LEXIS 233, at *24-25, and we agree. Therefore, our inquiry is limited to whether Decedent “retained ... the possession or enjoyment of’ the transferred 49% interest in the Manhattan property.
In applying the “possession or enjoyment” language of § 2036 “we look to substance, not to form.” Estate of Church, 335 U.S. at 644, 69 S.Ct. 322 (quoting Helvering v. Hallock, 309 U.S. 106, 114, 60 S.Ct. 444, 84 L.Ed. 604 (1940)). “It is well settled that the terms ‘enjoy’ and ‘enjoyment,’ as used in various estate tax statutes, ‘are not terms of art, but connote substantial present economic benefit rather than technical vesting of title or estates.’ ” Byrum, 408 U.S. at 145, 92 S.Ct. 2382 (quoting Comm’r v. Estate of Holmes, 326 U.S. 480, 486, 66 S.Ct. 257, 90 L.Ed. 228 (1946)). “In the case of real property, the terms ‘possession’ and ‘enjoyment’ have been interpreted to mean ‘the lifetime use of the property.’ ” Estate of Maxwell, 3 F.3d at 593 (quoting Byrum, 408 U.S. at 147, 92 S.Ct. 2382). While it may sometimes be difficult to determine who is using real property that is wholly inhabited by a decedent and/or family members, it is quite easy to determine who is using real property that is producing income. All we have to do is follow the money. Whoever is, in substance, receiving the net income (or taking the net loss) from the property, is using it during his or her lifetime, and thus possessing and enjoying the property. See Estate of McNichol v. Comm’r, 265 F.2d 667, 671 (3d Cir.1959); see also 26 C.F.R. § 20.2036-1(b)(2) (“The ‘use, possession, right to the income, or other enjoyment of the transferred property’ is considered as having been retained or reserved to the decedent to the extent that the use, possession, right to the income, or other enjoyment is to be applied toward the discharge of a legal obligation of the decedent, or otherwise for his pecuniary benefit.”).
Under the applicable Treasury Regulations, however, a finding of “retained ... possession or enjoyment” is not the end of the matter. The extent of the retained possession or enjoyment must also be determined.
If the decedent retained or reserved an interest or right with respect to all of the property transferred by him, the amount to be included in his gross estate under section 2036 is the value of the entire property, less only the value of any outstanding income interest which is not subject to the decedent’s interest or right and which is actually being enjoyed by another person at the time of the decedent’s death. If the decedent retained or reserved an interest or right with respect to a part only of the property transferred by him, the amount to be included in his gross estate under section 2086 is only a corresponding proportion of the amount described in the preceding sentence. An interest or right is treated as having been retained or reserved if at the time of the transfer there was an understanding, express, or implied, that the interest or right would later be conferred.
[156]*15626 C.F.R. § 20.2036—1(c)(1)(i) (emphasis added). This position is also the official position of the IRS, as well as at least one other circuit court. See Rev. Rul. 79-109, 1979-1 C.B. 297 (“[W]hen a decedent retained an interest in only a part of the transferred property, or, in the alternative, in a corresponding portion of the income produced by the property, the amount includible in the gross estate is that portion of the transferred property that would be necessary to yield the retained income.”); see also In re Estate of Uhl, 241 F.2d 867, 870-71 (7th Cir.1957).
As discussed earlier, one way a decedent can retain possession or enjoyment of a property is through an implied agreement. Under 26 C.F.R. § 20.2036-1(c), however, the existence or nonexistence of an implied agreement is not enough to resolve this case. The terms of the agreement also matter. If, for example, the facts were to indicate that, pursuant to an implied agreement, Decedent had retained 80% of the substantial present economic benefit of the transferred 49% interest in the Manhattan property, then only the “corresponding proportion” of the value of the entire 49% interest would be included in the Estate.
III. Implied Agreement
We now turn to the Tax Court’s findings of fact. The Tax Court found that there was an “implied agreement” that Margot Stewart “would retain the economic benefits” of the entire transferred interest in the Manhattan property.10 Whether there was such an implied agreement, and what its terms were, are questions of fact that we review for clear error. Estate of Maxwell, 3 F.3d at 594; see also Frank Lyon Co., 435 U.S. at 581 n. 16, 98 S.Ct. 1291 (“The general characterization of a transaction for tax purposes is a question of law subject to [de novo ] review. The particular facts from which the characterization is to be made are not so subject.”). When deciding whether there was an implied agreement, some amount of inference is necessary. In order to make such an inference “all facts and circumstances surrounding the transfer and subsequent use of the property must be considered.” Estate of Rapelje v. Comm’r, 73 T.C. 82, 86, 1979 WL 3799 (1979); accord Estate of Abraham v. Comm’r, 408 F.3d 26, 39 (1st Cir.2005); see also 26 C.F.R. § 20.2036-1. “[T]he burden is on the decedent’s estate to disprove the existence of any adverse implied agreement or understanding and ‘that burden is particularly onerous when intrafamily arrangements are involved.’ ” Estate of Maxwell, 3 F.3d at 594 (quoting Estate of Rapelje, 73 T.C. at 86). Because the Manhattan property was used partly as a residence and partly as an income-producing rental property, we shall consider whether the facts and circumstances surrounding either of these uses indicated an implied agreement, and if so, what the terms of that agreement were.
A. Residential Use
The Tax Court did not rely on Decedent’s continued residence in the Manhattan property for its finding that an implied agreement existed. See Estate of Stewart, 2006 WL 3018173, at *2-*3 2006 Tax Ct. Memo LEXIS 230, at *5-*7. But the Commissioner seems to rely on it in part. We, however, do not believe that the terms of any implied agreement can be read to provide that Decedent would retain enjoy[157]*157ment of the residential portion of Brandon’s 49% interest in the Manhattan property.
In residential transfer cases, “[i]n determining whether an implied agreement or understanding existed between the parties.... the courts have found two factors to be particularly significant: continued exclusive possession by the donor and the withholding of possession from the donee.” Estate of Spruill v. Comm’r, 88 T.C. 1197, 1225, 1987 WL 49324 (1987); accord Guynn v. United States, 437 F.2d 1148, 1150 (4th Cir.1971). The presence of both those factors is so damning that in cases where a decedent transfers a residential property but continues to live in it to the exclusion of the donee, the estate taxpayer has lost in every case of which we are aware because the taxpayer could not meet its burden.11 And, if Brandon had not lived in the Manhattan property for the entire time between the transfer and Decedent’s death, it would certainly not have been clear error had the Tax Court found an implied agreement that Decedent could have excluded Brandon from the Manhattan property during her life, and thereby had enjoyed the benefits of the residential part of his 49% interest and of his rights as a residential tenant in common.
In this case, however, neither of the two factors stated in Spruill is present. Decedent did not have exclusive possession of, nor did she exclude Brandon from, Brandon’s 49% interest in the Manhattan property-—or, for that matter, the entire property. Like other courts, we draw a distinction between cases where a decedent retains exclusive possession and withholds possession from the donee on the one hand, and “those cases where a residence jointly occupied by the donor and the donee has been held not includable in the donor’s gross estate,” Guynn, 437 F.2d at 1150, on the other. This case is of the latter sort. And despite the great burden faced by the taxpayer in all these cases, taxpayers have ivon in every case of which we are aware when those two crucial factors were favorable.12 In these cases a transferor’s “use of the property by occu[158]*158pancy after the transfer is a natural use which does not diminish [the] transferee^] enjoyment and possession and which grows out of a congenial and happy family relationship.” Estate of Gutchess v. Comm’r, 46 T.C. 554, 557, 1966 WL 1184 (1966).
Although co-occupancy of a residential premises by the related donor and donee is highly probative of the absence of an implied agreement and has repeatedly been held to satisfy the taxpayer’s burden, we need not and do not hold that that fact alone will always carry the burden as a matter of law. In some future case, a finding of an implied agreement between related co-occupants of residential real property might not be clearly erroneous. But where, as here, the Tax Court has made no specific findings relating to enjoyment of the residential portion of the property, and the Commissioner points to nothing besides the mere co-occupancy between the donor and the donee, a conclusion based on an implied agreement concerning the residential portion cannot stand.13 As a result, Decedent’s residen[159]*159tial use of part of the Manhattan property does not indicate an implied agreement that she would to any extent retain the substantial economic benefits of the residential portion of Brandon’s 49% interest.
B. Commercial Use
It was, however, not clearly erroneous for the Tax Court to find an implied agreement that Decedent would enjoy for her life the substantial economic benefit of some part—indeed, perhaps all—of the rental portion of the Manhattan Property. The Tax Court found that (1) “Decedent continued to receive the $9,000 monthly rent payments from Financial Solutions, Ltd.,” and (2) Brandon’s testimony was not credible. Estate of Stewart, 2006 WL 3018173, at *2-*3, 2006 Tax Ct. Memo LEXIS 230, at *6-*7. Those two findings are not clearly erroneous and must be upheld. Because the Estate has failed to provide a credible explanation as to why the entire rent payments went to Decedent, they support the Tax Court’s finding of an implied agreement.
C. Apportionment
For the reasons stated above, it was not clearly erroneous for the Tax Court to find an implied agreement, but it was clearly erroneous for the Tax Court to find that file terms of the agreement were such that Decedent would enjoy the substantial economic benefit of 100% of Brandon’s 49% interest in the Manhattan property. This is so because Brandon manifestly enjoyed, and Decedent did not, the benefits of the residential portion of the 49%. And, as we discuss below, even as to the commercial portion it seems likely that Decedent retained the benefits of less than the total 49%.
The question that remains is, therefore, what part of the 49% interest should be included in the Estate. It is for the Tax Court in the first instance to make the findings necessary to answer that question. Because the Tax Court appears to have treated § 2036(a)(1) as an all-or-nothing matter and did not consider whether Decedent had “retained or reserved an interest or right with respect to a part only of the property transferred,” 26 C.F.R. § 20.2036—1(c)(1)(i), the findings cited by the Tax Court—Decedent’s receipt of the rental income and the credibility determination as to Brandon’s testimony—do not provide a complete picture of the extent to which Decedent enjoyed the substantial economic benefit of Brandon’s 49% interest during her life. And, because the Tax Court did not consider “all facts and cir[160]*160cumstances surrounding the transfer and subsequent use of the property,” Estate of Rapelje, 73 T.C. at 86, it is appropriate to vacate and remand so that the Tax Court may do so.
In determining the apportionment of Brandon’s 49% interest, the Tax Court should use the approach adopted by the IRS in Rev. Rui. 79-109. In that ruling, a decedent conveyed to his adult children a vacation home, but he retained for his life the right to use it or, in the alternative, keep the rental payments, during the month of January each year. The Service explained that “the amount includible in the gross estate is that portion of the transferred property that would be necessary to yield the retained income.” Id. The rental value of the property for January was $600, which was 13.3% of the $4500 the property produced annually, and the Service therefore calculated that 13.3% of the value of the residence was to be included in the decedent’s gross estate. Id.
The facts are more complicated in the instant case, but the basic principle is the same: the portion of the property to be included in the gross estate is the portion that would be necessary to produce the income Decedent retained. The Tax Court must first determine how much of the substantial economic benefit generated by the 49% interest is attributable to the residential portion of the interest and how much is attributable to the commercial portion. Such a finding is essential because, at least insofar as gross income is concerned, Decedent received 100% of the economic benefit from the commercial portion of the 49% transferred, by receiving the rent payments, while Brandon received 100% of the economic benefit from the residential portion of that 49% by inhabiting it.
The Tax Court should then examine a factual finding that it made, but seemingly failed to take fully into account. Between the transfer of the 49% interest and Decedent’s death, Decedent paid Manhattan property expenses of $21,790.85,14 and Brandon paid Manhattan property expenses of $1,963. Estate of Stewart, 2006 WL 3018173, at *1, 2006 Tax Ct. Memo LEXIS 230, at *3. This finding is a double-edged sword. Payment of expenses attributable to a property is one of the indicia of ownership of that property, and Decedent paid most (but not all) of the expenses attributable to Brandon’s 49% interest. As a result, the Tax Court’s finding concerning expenses supports its finding that an implied agreement existed and hence the inclusion of a significant portion of the 49% interest in the Estate. But each dollar of Manhattan property expenses paid by Decedent also decreases the economic benefit she received. For [161]*161example, if A and B jointly own a rental property that generates $10,000 per month in rent and $5,000 per month in expenses, and A and B split the rent evenly but B pays all the expenses, then in substance A is getting the entire economic benefit of the property while B is getting nothing. Because “ ‘enjoyment’ ... connote[s] substantial present economic benefit,” Byrum, 408 U.S. at 145, 92 S.Ct. 2382 (internal quotation marks omitted), we think who paid what expenses must be taken into account in apportioning the 49% interest between the Estate and Brandon. In other words, the Tax Court must determine who received what portion of the net income from the 49% interest, rather than the gross income.15
Finally, the Tax Court apparently did not consider the distribution of the income and expenses from the East Hampton property at all. While the Tax Court was clearly under no obligation to credit Brandon’s testimony that he and Decedent intended to use the East Hampton income to set off the Manhattan income and then reconcile their accounts at year’s end, it may be worth considering on remand where the net income from the East Hampton property went. Although the Commissioner argues that the reference to “the property” in § 2036(a)(1) “does not provide for consideration of the decedent’s relationship to other property, regardless of its circumstantial association with the property at issue,” Appellee’s Br. at 22, we need not go that far. In some cases, consideration of other property may be useful to an accurate determination of who enjoyed the substantial economic benefit of a property. If, for example, Brandon and Decedent had formally split the rental income and costs of the Manhattan property 51%-49% but Brandon had allowed Decedent to take a portion of what should have been Brandon’s net income from the East Hampton property, and that amount equaled the income Brandon was entitled to from his 49% share of the Manhattan property, then consideration of the East Hampton property would be necessary to prevent an abusive transaction that would otherwise evade § 2036. At the other extreme, if Brandon and Decedent had jointly owned hundreds of other properties and there was no particular reason to think that the distribution of income from those properties was in any way related to the substantial economic benefit of the disputed property, then it would be incorrect to consider such other properties. We leave it to the Tax Court to determine, on remand, where this case falls along that spectrum and whether the distribution of net income from the East Hampton property is among the “facts and circumstances surrounding the transfer and subsequent use of the property,” all of which “must be considered,” Estate of Rapelje, 73 T.C. at 86.16
[162]*162IV. Conclusion
Because the Tax Court’s finding that the terms of the implied agreement between Decedent and Brandon provided that Decedent would enjoy 100% of the substantial economic benefit of Brandon’s 49% undivided interest in the Manhattan property was clearly erroneous, we vacate the judgment below and remand for further proceedings. Decedent “retained or reserved an interest ... with respect to a part only of,” 26 C.F.R. § 20.2036—1(c)(1)(i), Brandon’s 49% stake in the Manhattan property, which is what she transferred. On remand, the Tax Court should make the factual determinations necessary to determine the amount of the net income from Brandon’s 49% interest enjoyed by Decedent. Then the Tax Court can calculate the “corresponding proportion” of “the value of the entire property,” and include it in the Decedent’s gross estate under § 2036. See 26 C.F.R. § 20.2036-1(c)(1)(i).
We therefore VACATE the judgment below and REMAND this case for further proceedings consistent with this opinion.