Selling Your Buy-To-Let In 2026/27: The Complete CGT Calculation From Purchase To 60-Day Return
- MAZ
- 36 minutes ago
- 14 min read
Selling Your Buy-to-Let in 2026/27: The Complete CGT Calculation From Purchase to 60-Day Return
Selling a buy-to-let property in the 2026/27 tax year means working through four things in order: your allowable base cost, any reliefs that reduce the taxable gain, the £3,000 annual exempt amount, and the 18% or 24% Capital Gains Tax (CGT) rate that applies depending on your income, all within a 60-day reporting and payment deadline that runs from the date of completion. HMRC's own guidance on CGT rates confirms that from 6 April 2026, higher and additional rate taxpayers pay 24% on their gains, while basic rate taxpayers pay 18% on the portion of a gain that stays within their basic rate band, with the rates applying identically to residential property and other chargeable assets since October 2024.
Most of the calculation is arithmetic. The part that trips landlords up is knowing exactly what counts as an allowable cost, whether any period of past occupation still shelters part of the gain, and getting the 60-day return filed correctly before the standard Self Assessment deadline is even relevant. I walk through this calculation with clients constantly, and the mistakes I see are rarely about the headline rate. They are about missed costs, misapplied reliefs, and reporting deadlines treated as an afterthought.
Step 1: Establishing Your Base Cost
Your base cost is what you paid for the property plus the costs of acquiring it, plus the cost of any capital improvements made during ownership, minus anything already deducted elsewhere. This figure is deducted from your net sale proceeds to arrive at the gain before any reliefs or exemptions are applied.
Allowable acquisition costs include the purchase price itself, Stamp Duty Land Tax (or Land and Buildings Transaction Tax in Scotland, or Land Transaction Tax in Wales) paid on the original purchase, legal fees, and survey costs. Allowable improvement costs cover genuine capital additions, an extension, a loft conversion, a new kitchen where none existed before, or replacing a single-glazed window system with double glazing throughout. What is not allowable is anything that counts as repair or maintenance rather than improvement, a repainted wall, a replaced boiler like-for-like, a repaired roof. The distinction between repair and improvement is one HMRC scrutinises closely on property disposals, and the general test is whether the work restores the property to its previous condition (repair, not deductible against the gain, though it may already have been claimed against rental income) or genuinely enhances it beyond that condition (improvement, deductible against the gain).
Selling costs are deducted from proceeds rather than added to the base cost, but the effect on the final gain is the same. Estate agent fees, legal fees on the sale, and any costs of establishing title or defending the property's boundaries during the sale process are all allowable.
What You Cannot Deduct
Mortgage interest is not deductible against a capital gain under any circumstances. It is an income tax matter, addressed (in restricted form since April 2020) through the property income calculation, not the CGT computation, and landlords selling a heavily mortgaged property sometimes mistakenly try to bring interest costs into the gain calculation. Furniture, white goods, and other costs already claimed as a revenue deduction against rental income, including the replacement of domestic items relief, cannot also be claimed against the capital gain. The same cost cannot reduce both your rental profit and your capital gain.
Step 2: Applying the Annual Exempt Amount
Every individual has an annual exempt amount of £3,000 for 2026/27, unchanged from 2025/26 and considerably reduced from the £12,300 available as recently as 2022/23. This is applied after any allowable losses in the same tax year, and it cannot be carried forward if unused. A married couple or civil partners each have their own separate £3,000 exempt amount, meaning jointly owned property sold in a single tax year benefits from £6,000 of combined exemption between them, applied to each person's own share of the gain.
Step 3: Working Out the Rate: The Income Stacking Effect
This is the part landlords consistently underestimate. Your CGT rate is not a flat figure applied to the whole gain. The gain is treated as the top slice of your income for the year, stacked on top of your salary, pension, self-employment profit, or other taxable income, and taxed at 18% for the portion that falls within your remaining basic rate band, and 24% for anything above it.
For 2026/27, the basic rate band is £37,700, and the higher rate threshold, where income plus gains together exceed £50,270, is where the 24% rate begins to bite. A landlord earning £40,000 in salary who realises a taxable gain of £20,000 on a buy-to-let sale, for example, has already used most of their basic rate band through their salary. Only £10,270 of the gain falls within the remaining basic rate space and is taxed at 18%; the remaining £9,730 is taxed at 24%. This stacking effect means a landlord with a modest salary and a large gain can find a substantial portion of that gain taxed at the higher rate, even though their day-to-day income tax position looks entirely ordinary.
One detail worth flagging for landlords filing their 60-day return before the tax year has ended: HMRC accepts a reasonable estimate of your other income for the year when working out which rate applies at the point of filing, since you may not yet know your final income position. Any adjustment is trued up when you complete your Self Assessment return for the year, and a reasonable estimate made in good faith should not itself trigger a penalty even if it later proves slightly inaccurate.
What this Widget is About: This interactive calculator by My Tax Accountant is designed to help UK landlords estimate their Capital Gains Tax (CGT) liability when selling a buy-to-let property in the 2026/27 tax year. By processing your specific financial details, the tool provides a comprehensive breakdown of your taxable gain, applicable reliefs, and the final tax owed based on the current 18% and 24% property rates. To use the widget, simply enter your property purchase price, sale price, allowable capital costs, and total months of ownership into the designated fields. Next, input your estimated annual income and any periods you lived in the property as your main home to ensure Private Residence Relief (PRR) is accurately applied to your calculation. Once completed, the widget will instantly generate a clear, step-by-step visual summary of your CGT bill, empowering you to budget accurately well ahead of the strict 60-day HMRC reporting deadline.
If You Ever Lived There: Private Residence Relief and the Final Nine Months
Many buy-to-lets started life as someone's own home before being let out, and this changes the calculation considerably. Private Residence Relief (PRR) exempts the portion of the gain attributable to periods when the property was your only or main residence, and crucially, HMRC's helpsheet on Private Residence Relief confirms that the final nine months of ownership are always treated as a qualifying period, regardless of whether you actually lived there during that time, provided the property was genuinely your main home at some point during your ownership. This final period exemption was reduced from 18 months to 9 months for disposals on or after 6 April 2020, though it remains 36 months for those who are disabled or have moved into long-term residential care.
Where a property was your home for part of your ownership and let out for the rest, the exempt fraction is calculated as (months of qualifying occupation, including allowed absences, plus the final 9 months) divided by total months of ownership, applied to the total gain.
A further relief, lettings relief, can apply on top of PRR, but the rules changed substantially from 6 April 2020. It is now only available where you were in shared occupation with a tenant during the letting period, meaning you lived in the property alongside them, typically a lodger arrangement, rather than simply moving out and letting the whole property to someone else. Where the whole dwelling was let after you moved out, which describes most former-home-turned-buy-to-let situations, lettings relief simply does not apply, regardless of how long ago the letting began. This is one of the most consistently misunderstood points I encounter, since many landlords remember lettings relief from years ago when it worked very differently and assume the old, more generous version still applies.
A Worked Example
Take a landlord who bought a flat in June 2011 and lived in it as her main home until June 2016, five years, then let it out in full to tenants until she sold it in August 2026, a further ten years two months, giving total ownership of 182 months. Her qualifying period is 60 months of actual occupation plus the final 9 months, giving 69 months out of 182, or roughly 38%. If her total gain is £140,000, PRR exempts £53,077 of it, leaving £86,923 chargeable. Because she let the whole flat rather than sharing occupation with a tenant, no lettings relief applies to the remaining chargeable amount. That £86,923, less her £3,000 annual exempt amount, is then taxed at 18% or 24% depending on her income for the year.
Furnished Holiday Lets: What Changed From April 2025
If your buy-to-let was previously operated as a Furnished Holiday Let (FHL), the position changed materially with the abolition of the FHL tax regime from 6 April 2025. Before that date, qualifying FHL properties could access Business Asset Disposal Relief on sale, at a considerably lower rate than standard property CGT, along with capital allowances not available to ordinary rental property. From 6 April 2025 onwards, FHL properties are treated the same as any other residential letting for tax purposes, meaning a sale in 2026/27 no longer carries any prospect of the reduced BADR rate that a similar disposal might have attracted a few years earlier. Landlords who converted a former holiday let into a standard tenancy, or who are now selling a property that once qualified as an FHL, should not assume any of the old FHL-specific reliefs still apply to a 2026/27 disposal.
UK Buy-to-Let CGT 2026/27 Lifecycle Summary
Calculation Stage | Description & Key Components | Requirements & Compliance Rules |
1. Base Cost and Allowable Enhancements | Establish the initial purchase price plus acquisition costs (legal fees, Stamp Duty). Add allowable capital enhancements that add permanent value (e.g., extensions, loft conversions). Exclude revenue repairs (e.g., painting, maintenance, fixing leaks) as these are not deductible for CGT. | Distinguish capital costs from revenue repairs; only the former reduces the gain. Maintain original invoices and completion statements for at least 6 years. Revenue repairs are deducted from rental income, not capital gains. |
2. Chargeable Gain and Rate Application | Subtract the total cost basis and selling fees (estate agent, legal) from the disposal price. Deduct the Annual Exempt Amount ( $AEA$ ) of $£3,000$ (for individuals in 2026/27). Apply rates of 18% for unused basic rate bands and 24% for higher or additional rate taxpayers. | The $£3,000$ allowance is per individual; spouses can combine allowances to shelter $£6,000$ if jointly owned. The rate is determined by "stacking" the gain on top of other taxable income for the year. |
3. 60-Day Digital Reporting and Payment | Report the disposal and pay the estimated tax due via the "Capital Gains Tax on UK Property" digital service. This standalone return is separate from the annual Self-Assessment system. | Strict 60-day deadline from the date of completion (not exchange) for both reporting and payment. Failure to comply results in an immediate $£100$ penalty, plus interest and potential further fines. |
The 60-Day Return: What It Actually Requires
Where CGT is due on the disposal of UK residential property, HMRC's guidance on reporting and paying confirms the return and an estimated payment must reach HMRC within 60 days of the completion date, not the date contracts were exchanged. This is filed through a dedicated Capital Gains Tax on UK Property account, entirely separate from Self Assessment, and it must be set up in advance using Government Gateway credentials before a return can be submitted.
The 60-day rule does not apply where no CGT is actually due on the disposal, for example where the gain is fully covered by PRR, by the annual exempt amount, or by losses available to offset it. It does apply, however, to every other disposal producing a chargeable gain, and missing the deadline triggers an automatic penalty regime: an immediate £100 penalty, rising to a further £300 or 5% of the tax due (whichever is greater) if the return remains outstanding six months after the deadline, another £300 or 5% at twelve months, plus daily penalties of £10 accruing after three months. Interest also accrues on any unpaid tax from the original due date.
If you also complete a Self Assessment return for the year, the same gain must be reported again on that return, alongside the CGT already paid and the 14-character payment reference generated by the 60-day return, so HMRC can reconcile the two and avoid a duplicate charge. Landlords who file the 60-day return correctly sometimes forget this second step, and while it does not create an additional tax liability, an inconsistent Self Assessment return can trigger an unnecessary HMRC query.
Spousal Transfers Before a Sale
Transfers of assets between spouses and civil partners who are living together are treated as no gain, no loss for CGT purposes, meaning no tax arises on the transfer itself. Where one spouse is a higher rate taxpayer and the other has unused basic rate band, transferring a share of a jointly held buy-to-let to the lower-taxed spouse before completion, and using both individual £3,000 annual exempt amounts, can produce a genuine and entirely legitimate reduction in the combined CGT bill. This needs to be done with a proper transfer of legal and beneficial ownership before the sale is agreed, not as a paper exercise after contracts are exchanged, and mortgage lender consent is usually required where the property is mortgaged.
Scotland and Wales: No Separate CGT Regime
Capital Gains Tax is reserved to the UK government and is not devolved to Scotland or Wales, so the rates, the annual exempt amount, PRR, and the 60-day reporting rule all apply identically regardless of where in the UK the property is located or where the seller is resident. One point worth stating explicitly for Scottish landlords: although Scottish Income Tax uses different bands and thresholds from the rest of the UK, the £37,700 basic rate band used to work out where a capital gain sits for CGT stacking purposes is the UK-wide figure, not the Scottish starter, basic, or intermediate rate bands. A Scottish taxpayer's income tax position uses Scottish rates, but their CGT rate calculation uses the same UK-wide thresholds as a taxpayer in England or Wales.
What this Widget is About: This interactive widget gives UK landlords a clear, step-by-step guide to calculating Capital Gains Tax when selling a buy-to-let property in the 2026/27 tax year, covering everything from establishing your base cost and applying reliefs to the 18% or 24% rates and the strict 60-day reporting deadline. It explains the key rules in plain language, including what counts as an allowable cost, how the £3,000 annual exempt amount works, the income-stacking effect that determines your rate, Private Residence Relief with its final nine-month rule, and why lettings relief rarely applies any more. You can move between the tabs to read the explanations, view worked examples and practical checklists, or jump straight to the Interactive Calculator. Simply enter your sale proceeds, purchase price, costs, other income and any previous occupation details, then click the button to see an instant estimate of your chargeable gain and potential tax bill. The figures are based on current HMRC guidance for illustration only, so always double-check with a qualified adviser for your personal situation before filing.
Practical Steps Worth Taking
● Gather every acquisition, improvement, and selling cost document before completion, since these need to be finalised for the 60-day return, not assembled afterwards.
● Check carefully whether any cost claimed against rental income over the years, including the replacement of domestic items relief, has already been used, since it cannot also reduce the capital gain.
● If the property was ever your main home, work out the PRR fraction precisely, including the automatic final 9 months, before assuming the whole gain is chargeable.
● Confirm whether lettings relief genuinely applies, remembering that it is now restricted to periods of shared occupation with a tenant, not simply any period of letting after you moved out.
● Diarise the 60-day deadline from the completion date the moment a sale is agreed, and set up the Capital Gains Tax on UK Property account in advance rather than at the last minute.
Key Takeaways
The CGT calculation on a buy-to-let sale is straightforward in principle, proceeds minus costs minus reliefs minus the annual exempt amount, taxed at 18% or 24% depending on where the gain sits against your income. Where it goes wrong in practice is in the detail: costs claimed twice, lettings relief assumed to apply when it no longer does, and a 60-day deadline treated with less urgency than it deserves given the size of the penalties attached to missing it.
FAQs
What CGT rate will I pay on selling my buy-to-let in 2026/27?
You will pay 18% on the portion of your gain that falls within your remaining basic rate band for the year, and 24% on any portion above the £50,270 higher rate threshold, once your gain is stacked on top of your other taxable income.
Can I deduct mortgage interest from my capital gain when I sell?
No. Mortgage interest is never deductible against a capital gain. It is treated separately as a restricted income tax deduction against rental profits, not as a cost of the property for CGT purposes.
Does lettings relief still apply if I lived in the property and then let it out completely?
Not since 6 April 2020. Lettings relief now only applies where you shared occupation with a tenant, meaning you lived in the property alongside them. If you moved out and let the whole property to tenants, lettings relief does not apply, regardless of how long ago the letting began.
How is the final period exemption calculated under Private Residence Relief?
The final 9 months of ownership are always treated as a qualifying period for relief, provided the property was your only or main residence at some point during your ownership, even if you were not living there during those final 9 months. This applies to disposals on or after 6 April 2020; the period was 18 months before that date.
What is the deadline for reporting and paying CGT on a property sale?
You must report the disposal and pay any estimated CGT within 60 days of the completion date, not the date contracts were exchanged, using HMRC's Capital Gains Tax on UK Property account.
What happens if I miss the 60-day deadline?
An automatic £100 penalty applies immediately, rising to a further £300 or 5% of the tax due at six months, another £300 or 5% at twelve months, plus daily penalties of £10 after three months, along with interest on any unpaid tax.
Does the CGT rate work differently for landlords in Scotland?
No. Capital Gains Tax is reserved to the UK government, so Scottish landlords pay the same 18%/24% rates and use the same UK-wide £37,700 basic rate band for CGT purposes as landlords elsewhere in the UK, even though Scottish Income Tax itself uses different bands.
Can transferring my buy-to-let to my spouse before selling reduce our CGT bill?
Potentially, yes. Transfers between spouses and civil partners living together are treated as no gain, no loss, so transferring a share to a spouse with unused basic rate band or an unused annual exempt amount before completion can reduce the combined tax owed, provided the transfer is genuine and completed before the sale is agreed.
Does my old Furnished Holiday Let still qualify for a lower CGT rate?
No. The Furnished Holiday Lettings regime was abolished from 6 April 2025, so a disposal in 2026/27 is treated the same as any other residential property sale, with no access to the reduced Business Asset Disposal Relief rate that FHL properties could previously claim.
About the Author
Maz Zaheer, AFA, MAAT, MBA, is the CEO and Chief Accountant of MTA and Total Tax Accountants, two premier UK tax advisory firms. With over 15 years of expertise in UK taxation, Maz provides authoritative guidance to individuals, SMEs, and corporations on complex tax issues. As a Tax Accountant and an accomplished tax writer, he is renowned for breaking down intricate tax concepts into clear, accessible content. His insights equip UK taxpayers with the knowledge and confidence to manage their financial obligations effectively.
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