Section 121 exclusion for vacant land sold before primary residence

Quick answer: For 2025, whether the sold parcel qualifies for any § 121 exclusion doesn't turn on the mortgage — it turns on whether that parcel was "vacant land" adjacent to and part of the residence, sold within the required time window relative to the house sale. Since he still owns and lives in the house, the sale of the other parcel last year likely does not yet qualify for exclusion — but it may become eligible retroactively once he sells the house, if the timing rules are met. He may be able to file an amended return at that point.

What it is

Section 121 excludes gain on the sale of a taxpayer's principal residence if, during the 5-year period ending on the sale date, he owned and used the property as his principal residence for at least 2 years, up to $250,000 of gain per sale ($500,000 for certain joint returns)¹. This applies to "the sale of property" used as the residence — it does not automatically extend to every parcel financed under the same mortgage. A separate, unattached parcel is not the residence itself.

However, Treasury regulations do address exactly this situation for vacant land sold separately from the dwelling. Treas. Reg. § 1.121-1, last amended in 2002, provides a special rule: if the sale or exchange of the dwelling unit occurs in a later taxable year than the sale or exchange of the vacant land and after the due date (with extensions) for the return covering the vacant land sale, any gain from the vacant land sale must be treated as taxable on the return for that earlier year.²

How it works

The regulation's own example matches his facts closely. In Example 3, a taxpayer buys a house and 10 acres, later sells 8 acres separately (a gain that, standing alone, isn't yet excludable), and sells the house and remaining acreage in a later year. The regulation explains: In 1991 Taxpayer C buys property consisting of a house and 10 acres that she uses as her principal residence. In May 2005 C sells 8 acres of the land and realizes a gain of $110,000. C does not sell the dwelling unit before the due date for filing C's 2005 return, therefore C is not eligible to exclude the $110,000 of gain. In March 2007 C sells the house and remaining 2 acres realizing a gain of $180,000 from the sale of the house. C may exclude the $180,000 of gain. Because the sale of the 8 acres occurred within 2 years from the date of the sale of the dwelling unit, the sale of the 8 acres is treated as a sale of the taxpayer's principal residence under paragraph (b)(3) of this section. C may file an amended return for 2005 to claim an exclusion for $70,000 ($250,000-$180,000 gain previously excluded) of the $110,000 gain from the sale of the 8 acres.³

Applying that to him: last year's sale of the second parcel was correctly reported as fully taxable (assuming he wasn't selling the house at the same time), because the house sale hadn't happened yet. But if he sells the house within 2 years of last year's parcel sale, the earlier sale can retroactively be treated as part of the principal-residence sale, and he can amend that year's return to claim exclusion on however much of the $250,000/$500,000 limit remains after applying it to the house-sale gain.

Risks and limits

• This treats vacant land, not a business parcel with a structure. The regulation's rule is specifically for "vacant land." If the sold parcel had his garage/contracting business on it, that changes the analysis — a separate business structure isn't "vacant land" and likely doesn't qualify at all under this rule.
• Business/rental use within a single dwelling unit is different from a separate parcel. Publication 523 warns that space separate from the living area — you generally can't exclude gain on the separate portion of your property used for business or to produce rental income.⁴ If the garage is a separate structure used for the S-corp business, gain attributable to it is not part of the residence exclusion regardless of the parcel/mortgage question.
• Ownership and use requirements still apply to the house parcel when he eventually sells it — 2 of the last 5 years as principal residence.
• The combined exclusion is capped at $250,000 single / $500,000 joint total, split between the two sales, not doubled.
• Timing is strict: the amendment route in the regulation only works if the house sale happens within the window described, and if the statute of limitations for amending the parcel-sale year hasn't expired.

In practice

He likely can't claim anything on last year's return right now. The right move is to wait and see: if he sells the house parcel within 2 years of the parcel sale, and it otherwise qualifies as his principal residence, he may be able to amend last year's return to retroactively exclude the applicable share of last year's $52,000 gain. But the fact that a business/garage may sit on the sold parcel — separate from the residence — is a serious complication these documents don't fully resolve for your facts.

Given the mixed business use, the S-corp involvement, and the multi-parcel/single-mortgage structure, this is a fact-intensive situation where a CPA should review the deed, parcel history, and depreciation records before you file anything (including any amended return) — get Hopkins CPA Firm involved before the house sale closes, not after.