US UK Tax Returns Preparation: Selling a UK Garden Plot

When an American living in Britain sells part of the garden of a UK home as a building plot, each country taxes it separately. UK private residence relief usually covers the plot only if it sits within the permitted area and is sold before or with the house. The US exclusion covers it only if the house itself is sold within two years. Both returns must be built from the same completion statement.

That is the short answer. The detail is where six-figure differences arise. For most clients, the money is not in choosing a strategy. It is in getting US UK Tax returns preparation right once the plot has already sold: the right cost apportioned in each currency, the 60-day UK property return filed or correctly not filed, and the US Schedule D reflecting a regulation most preparers have never read. At Jungle Tax we prepare these returns from the legal paperwork, not from estimates. This guide sets out how both systems treat a garden plot sale, where they disagree, and how to correct earlier years if the sale was missed.

Why does a garden plot sale cause problems on both returns?

A large garden in a desirable postcode can be worth more as a building plot than many houses. A buyer with planning permission (or the prospect of it) will often pay a substantial sum for a strip of lawn or an old orchard. Because the land was bought decades ago as part of a family home, the cost attributable to it is small. The gain is therefore large, and the question of relief is decisive.

The difficulty for a US citizen or green card holder resident in the UK is that the two home-sale reliefs were drafted for different problems:

• UK private residence relief (PRR) is a full exemption with no monetary cap. It asks whether the land was garden or grounds of your only or main residence at the moment you sold it, and whether it fell within the "permitted area".
• The US section 121 exclusion has a monetary cap of $250,000 per individual ($500,000 on most joint returns). It treats vacant land as part of a residence only if the dwelling itself is sold in a qualifying sale within two years before or after the land sale.

So the same sale can be fully exempt in the UK and fully taxable in the US, or the reverse. No foreign tax credit bridges that gap, because a credit only works where both countries tax the same gain.

How does UK private residence relief treat part of a garden?

HMRC's helpsheet on private residence relief (HS283) extends relief to land you occupy and enjoy as the garden or grounds of your main residence. Selling part of that land can attract full relief, on four conditions.

1. The plot must be within the permitted area

The permitted area is half a hectare (roughly 1.24 acres), including the footprint of the house. If the garden and grounds do not exceed half a hectare, all of it is within the permitted area. Above that, relief extends only to the area "required for the reasonable enjoyment" of the house as a residence, given its size and character. For a substantial country house that may justify more than half a hectare, but the burden is on the taxpayer. HMRC can refer the question to its valuers. Where the garden exceeds half a hectare and you claim relief on a sale of land, the helpsheet asks you to report the disposal and explain the claim on your return.

2. It must be garden or grounds at the date of sale

Land that has been fenced or divided off from the garden for development, or that has been developed or is being developed (foundations dug, access road laid, services trenched) at the date of disposal, falls outside the relief. A grant of planning permission alone does not end garden status. Physically separating the plot and starting work generally does. Tribunal decisions have gone both ways on intermediate facts, so contemporaneous photographs and evidence of continued garden use are worth keeping for the return file.

3. It must be sold before, or together with, the house

This is the rule that catches most families. If you sell the house first and the plot afterwards, the plot is no longer the garden of your residence when you sell it, and relief is lost entirely. That follows the long-standing Varty v Lynes line of authority, which HMRC's guidance reflects. Selling the plot first, while you still live in the house, or in the same transaction, keeps the relief available.

4. The usual PRR conditions must still be met

The house must have been your only or main residence. Periods of letting, business use or absence can restrict relief for the house and its grounds alike. If you own more than one residence and have made a main-residence nomination, the nomination governs.

What does the US say about selling vacant land next to your home?

Section 121 lets you exclude up to $250,000 of gain ($500,000 for married couples filing jointly where both meet the use test and either meets the ownership test) on the sale of your principal residence. You must have owned and used it as your main home for at least two of the five years before the sale. The exclusion applies to a UK home exactly as it would to a US one; see IRS Publication 523.

The vacant land rule in Treasury Regulation section 1.121-1(b)(3) decides whether a garden plot sold on its own counts. The sale of vacant land is treated as a sale of your principal residence only if:

• the land is adjacent to the land containing the dwelling;
• you owned and used the land as part of your principal residence;
• you sell the dwelling in a sale that qualifies for the exclusion within two years before or two years after the land sale; and
• the other section 121 requirements are met for the land.

Where these are met, the land sale and the house sale are treated as one sale for the cap. Together they share a single $250,000 or $500,000 limit, not one each. Neither sale counts against the other for the once-every-two-years rule.

The plot is sold first and the house later

If the house is sold in a later tax year, and after the due date (including extensions) of the return for the year the plot was sold, the regulation requires you to report the plot gain as taxable in that year. When the house sale later qualifies, you claim the exclusion for the plot on an amended return, provided the refund period is still open. In practice, if the house sale is genuinely expected, extending the US return for the plot year can avoid the amend-later cycle. Americans abroad already have an automatic extension to June 15 and can extend to October 15.

The plot is sold and the house is kept

This is the case most UK-resident Americans are in, and the one generalist articles miss. If you sell off the bottom of the garden and stay in the house for more than two years afterwards, the plot sale never qualifies under section 121. The whole US gain is taxable as long-term capital gain, and is usually net investment income as well. In the UK the same sale is often fully covered by PRR. You can end up paying US tax at up to 23.8% on a gain the UK does not tax at all, with no UK tax to credit against it.

US vs UK: how the same plot sale is treated

Situation	UK (HMRC)	US (IRS)
Plot sold while you still live in the house; house kept long term	PRR usually available if within the permitted area and not fenced off or developed	Not a principal residence sale; gain fully taxable (plus NIIT where applicable)
Plot sold, house sold within two years afterwards	PRR usually available on the plot; house covered separately	Plot and house share one $250k/$500k exclusion; amended return may be needed
House sold first, plot sold within two years afterwards	No PRR on the plot; CGT at 18%/24% on the gain	Plot can share the exclusion if owned and used as part of the residence
House sold first, plot sold more than two years later	No PRR; fully chargeable	No exclusion; fully taxable, with credit for UK CGT
House and plot sold to different buyers on the same day	PRR available on both, subject to permitted area	Treated as one sale; single exclusion cap applies
Garden larger than half a hectare	Relief limited to the area needed for reasonable enjoyment; excess chargeable	No acreage test; the question is use as part of the residence
Reporting deadline	60-day UK property return if CGT is due, then Self Assessment by 31 January	Form 1040 for the calendar year; Form 8949 and Schedule D
Currency	Sterling throughout; no currency gain	Each figure translated to dollars at its own date; FX movement is part of the gain

Apportioning the cost: two methods that rarely agree

Whatever relief applies, both returns need a cost for the slice of land sold. The two systems get there differently.

UK: the part-disposal formula

For a part disposal, UK law apportions the original cost using the formula A / (A + B). A is the sale proceeds of the part sold and B is the market value of the part retained at the date of the sale. If the plot sells for £650,000 and the house with its remaining garden is worth £2,600,000, one fifth of the original purchase price (plus a fifth of qualifying improvement costs to the whole) is allocated to the plot. The retained value needs a supportable valuation, ideally from a chartered surveyor, kept with the return.

US: equitable apportionment of basis

US rules require the basis of the whole property to be equitably apportioned between the parts. In practice this usually means relative values at acquisition, when the land was simply garden with no development value. That often gives the plot a much smaller share of basis than the UK formula does, and a larger US gain. Improvements must be traced to the part they benefited; a new kitchen is house basis, not plot basis. Any depreciation claimed on the US side for a home office or letting reduces basis and cannot be excluded.

Selling costs and planning costs

Legal fees, selling agent fees and the cost of obtaining planning permission are generally deductible in both systems, as costs of sale or as enhancement of the land sold. Costs shared between the plot and the house, such as a planning application covering access changes to both, should be apportioned on a consistent basis and documented.

Worked example: a garden plot sold, the house retained

Consider a married couple, both US citizens, resident in the UK and filing jointly in the US. All figures, including exchange rates, are illustrative only.

• House and 0.45 hectares of garden bought jointly in 2014 for £1,500,000, when £1 bought $1.65.
• Outline planning permission obtained for one dwelling at the end of the garden. Plot sold in 2026 for £650,000, when £1 bought $1.33. Legal, agency and planning costs total £20,000.
• House with its remaining garden valued at £2,600,000 at completion. The couple remain in the house.

UK return. Allocated cost is £1,500,000 × 650 / 3,250 = £300,000. The gain is £650,000 − £300,000 − £20,000 = £330,000. The whole garden is under half a hectare, the plot was sold while the house was their main residence, and it had not been fenced off or developed. PRR covers the entire gain, so no UK CGT is due. Because no tax is payable, no 60-day UK property return is required. The disposal should still be reviewed for disclosure on the Self Assessment return.

US return. Assume a surveyor's report shows the plot represented about 10% of the 2014 value, so US basis is £150,000 × 1.65 = $247,500. The amount realised is (£650,000 − £20,000) × 1.33 = $837,900. The long-term capital gain is $590,400. The house is not being sold, so section 121 does not apply. At a 20% capital gains rate plus 3.8% net investment income tax, US tax could approach $140,000, with no UK tax to credit against it.

On the UK-formula basis instead (£300,000 × 1.65 = $495,000), the US gain would be $342,900. The choice of apportionment method alone moves the US gain by roughly $250,000. That is why the valuation evidence in the return file matters as much as the arithmetic.

Currency: the gain that exists only in dollars

The US measures everything in dollars. Basis is translated at the exchange rate on the purchase date (with improvements at their own dates). The amount realised is translated at the rate on the sale date. When sterling has weakened since purchase, as it has against most purchase dates from the late 2000s and early 2010s, the dollar gain can be smaller than the sterling gain. When sterling has strengthened, the reverse is true. You can even have a sterling loss and a dollar gain on the same plot.

Separately, if part of a sterling mortgage is redeemed from the plot proceeds, the repayment can trigger a US foreign currency gain on the debt under the section 988 rules. That gain is ordinary income, does not benefit from the home-sale exclusion and has no UK equivalent. Partial redemptions are easy to overlook because the completion statement simply shows a lender payout.

UK reporting: the 60-day return and Self Assessment

A garden plot counts as residential property for UK reporting, because land enjoyed with a dwelling as garden or grounds falls within the definition. A UK resident who sells UK residential property must report and pay capital gains tax within 60 days of completion where tax is due. If PRR covers the whole gain, no 60-day return is needed. If PRR is partial, or lost because the house was sold first, the return and payment are due within 60 days. The gain must then also appear on the Self Assessment return for the tax year, due by 31 January following 5 April.

Rates are currently 18% within the basic-rate band and 24% above it, after the £3,000 annual exempt amount. If you have since left the UK, non-residents must file a 60-day return for any disposal of UK land, even where no tax is due.

US reporting: Form 8949, Schedule D and foreign tax credits

A UK sale will not produce a Form 1099-S. That does not remove the reporting obligation. A taxable plot gain belongs on Form 8949 and Schedule D, with basis and proceeds translated as above. Where the exclusion applies and the full gain is covered, reporting is not always mandatory, but in cross-border cases we normally show the sale and the exclusion so the position is visible and consistent with the UK return.

Where UK CGT is paid on a gain the US also taxes, a foreign tax credit is claimed on Form 1116. Three points regularly go wrong:

• Timing. The UK tax year runs to 5 April and the US year to 31 December. UK CGT paid on a 60-day return relates to a UK year that straddles two US years. The credit must be matched to the correct US year.
• Mismatched relief. Where the US excludes the gain but the UK taxes it (house first, plot within two years), the UK CGT has no US tax to offset in that category. Unused credits may be carried back one year or forward ten, which is valuable only if other foreign-source income of the same category arises.
• Net investment income tax. The IRS position is that foreign tax credits do not reduce the 3.8% NIIT. Treaty-based arguments exist but are contested and fact-specific, and should be taken only on a properly disclosed return.

The proceeds themselves have consequences. A six- or seven-figure sterling deposit will usually change the maximum balances you report on your FBAR (FinCEN Form 114) and on Form 8938. If accounts receiving the proceeds were never reported, use our FBAR penalty calculator to see what is at stake before you decide how to correct it.

Preparing both returns from the same completion statements

The most reliable approach is to treat the conveyancing file as the single source of truth and build both returns from it:

1. Gather the documents. The original purchase completion statement and title plan, the plot sale completion statement and transfer plan (TP1), the planning decision notice, invoices for planning, legal and agency costs, and any mortgage redemption statement.
2. Establish the facts each relief turns on. The total area of garden and grounds, whether the plot was fenced or worked on before completion, the dates of occupation, and whether and when the house itself was or will be sold.
3. Obtain valuations. The retained-part value at the sale date for the UK formula, and a supportable allocation at acquisition for US basis.
4. Compute the sterling gain and the UK relief, then decide whether a 60-day return was required.
5. Translate each element into dollars at its own date, apply the vacant land rule, and quantify any section 988 gain on mortgage repayment.
6. Reconcile the two computations line by line so the explanation for every difference (apportionment, currency, relief) is documented in the file. A tax authority query is then answered from the file, not reconstructed years later.

Our US-UK tax accountants prepare the federal return, the UK Self Assessment return and any 60-day return together for exactly this reason. A difference that is explained is defensible. A difference that is unexplained looks like an error.

What if the plot sale was left off an earlier return?

Garden plot sales are frequently missed. The money arrives through a solicitor, no 1099-S issues, and families often assume that "main home" relief covers it in both countries. Correction is straightforward if it is done before either tax authority asks.

Correcting the US side

If US returns were filed but omitted the gain, an amended return on Form 1040-X is the usual route, with a Form 1116 for any UK tax paid. Where the house was later sold within two years, the amended return may also be the place to claim the exclusion for the plot under the regulation described above. If US returns were not filed at all (common among accidental Americans who discover their status when a UK bank or solicitor asks), and the failure was non-wilful, the IRS Streamlined Foreign Offshore Procedures allow you to file the last three years of returns and six years of FBARs, generally without penalty for those meeting the non-residency test.

Correcting the UK side

A Self Assessment return can be amended within twelve months of the 31 January filing deadline. Outside that window, an omitted gain or a missed 60-day return is corrected through HMRC's disclosure facilities, with interest and, depending on behaviour, penalties. A missed 60-day return where the plot was fully covered by PRR generally does not arise, because no return was required. Confirming that conclusion and documenting why is still worthwhile. Our UK tax services team handles these disclosures alongside the US catch-up, so the figures match.

Points sophisticated sellers most often miss

• Joint ownership with a non-US spouse. Only the US citizen's share of the gain is reported, and the exclusion on a separate return is capped at $250,000.
• A garden partly let or used for business. A paddock let for grazing or a garden office used by a company is outside PRR and may be outside section 121. Apportionment then becomes three-way.
• Building the house yourself and selling it. If you develop the plot rather than sell it, the profit may be trading income in the UK, not a capital gain, and the US analysis changes too.
• Overage or clawback payments. Further sums triggered by later planning consents are additional proceeds. Each country needs them reported when they arise, and the dollar rate on that date applies.
• Ownership and use periods. A home acquired recently, or let before you moved in, may fail the US two-out-of-five-year test, or face partial non-qualifying use reductions, even where UK relief is unaffected.

For more on how high-value property transactions interact across both systems, see our library of cross-border guides.

Confidential help with your garden plot sale

Whether the plot completed last month or several years ago, the answer depends on the documents: the plans, the valuations, the dates and the exchange rates. We prepare the US and UK returns together from one set of figures. We file 60-day returns where they are due, claim the vacant land exclusion where it is available, and correct earlier years quietly where the sale was missed. To arrange a confidential review of your position, contact our cross-border team.