Buy-to-Let Capital Gains Tax Calculator (2026/27)
The 18/24% split against your real basic-rate band, the £3,000 allowance, joint shares — and the 60-day deadline most sellers learn about too late.
Your CGT, estimated
60-day rule: UK residential CGT must be reported and paid within 60 days of completion — not at year-end. Estimate ignores PRR/lettings relief and losses. Not advice.
How buy-to-let CGT actually works in 2026/27
Sell a rental property for more than it cost you (after buying costs, selling costs and capital improvements) and the gain above the £3,000 annual exempt amount is taxed at 18% where it fits inside your unused basic-rate band and 24% above it. The Budget of November 2025 left all of this untouched — rates, allowance, and the rule people miss most:
The 60-day clock. CGT on UK residential property is reported and paid within 60 days of completion through HMRC’s property-disposal service — not in your January tax return. Miss it and penalties run even if the year-end return is perfect.
What moves the number
- Your income in the sale year. The 18% band is whatever basic-rate band your income hasn’t used. A £30,000-income seller gets ~£20,000 of gain at 18%; a £60,000-income seller gets none.
- Joint ownership doubles the allowance and splits the gain — spouses can also transfer between themselves tax-free before selling to use both bands. (Planning territory: take advice.)
- Improvements vs repairs. An extension raises your cost base here; a repaired roof was an income-tax expense in the year you did it — it cannot be counted again.
- If you ever lived there, Private Residence Relief exempts those years plus the final 9 months, and shared-occupancy lettings relief can add up to £40,000 — our calculator deliberately leaves these out rather than half-model them; if they apply to you, your number is lower than shown.
Pre- vs post-2024 purchases — one thing that no longer matters, one that does
The old taper rules apply to income-tax-side property questions, not CGT: for CGT there is no holding-period discount at all — a plot held 20 years and a flat held 20 months pay the same rates. What does still matter is the acquisition value: inherited property uses market value at the date of death, and gifted property from a spouse carries their original base cost.
gov.uk Capital Gains Tax rates · HS283 (Private Residence Relief) · Saffery Autumn-Budget-2025 review (no CGT change). Checked 29 Aug 2026.
Asked constantly
18% on gain that fits in your unused basic-rate band, 24% above it, after the £3,000 annual exempt amount. Example: £60,000 gain, £45,000 income → about £5,270 of unused basic band at 18%, the rest at 24% — roughly £13,400. The calculator above does your exact split.
Within 60 days of completion, through HMRC's UK-property reporting service — payment on account included. The gain then also goes on your Self Assessment for the year. The 60-day deadline is the one sellers miss.
The legitimate levers: sell in a low-income year (more 18% band); use joint ownership so both allowances and bands count (interspousal transfers are tax-free); make sure every buying cost, selling cost and genuine capital improvement is in your cost base; offset capital losses; and if you ever lived in the property, claim PRR for those years plus nine months. Schemes beyond that are adviser territory — and often don't survive contact with HMRC.
No — residential rates stayed 18/24% and the allowance stayed £3,000. The Budget's property move was on income tax: new 22/42/47% rates on rental income from April 2027. Different tax, different date — our tax-changes guide keeps the two straight.