CGT Allowance Tracker UK

Capital Gains Tax is what HMRC charges when you sell, gift, transfer or otherwise dispose of an asset worth more than you paid for it. For UK investors, the most common scenarios are selling shares or funds held outside an ISA or SIPP, selling a second property, or transferring chargeable assets to anyone other than a spouse or civil partner. The 2026/27 tax year started on 6 April 2026 and runs to 5 April 2027.

Three numbers do most of the work. Your £3,000 annual exempt amount is the slice of gains you can realise each tax year without paying any tax. The 18% rate applies to gains falling within your unused basic-rate income band. The 24% rate applies to anything above. Those two rates have been the standard rates for non-residential disposals since 30 October 2024 — they replaced the old 10% / 20% rates in the Autumn Budget.

The current rate card

If your gain straddles both bands — for example, you earn £45k and realise a £20k taxable gain — the bit that fits inside your remaining £5,270 basic-rate room is taxed at 18%, the rest at 24%. The tool above handles this automatically when you pick "Some band remaining (split rate)" and enter the basic-rate band you have left.

Scotland — same CGT, despite different income tax

If you're a Scottish taxpayer, your income tax bands differ from the rest of the UK — the Scottish basic rate ends at £26,561 and the intermediate, higher and top rates apply above that. CGT is not devolved. Even though you pay Scottish income tax, your CGT rate is determined by the UK-wide basic-rate threshold of £50,270.

So a Scottish higher-rate income taxpayer earning £45,000 still has £5,270 of "basic-rate room" for CGT purposes (£50,270 − £45,000), even though they're already in the Scottish intermediate band for income tax. The gain within that £5,270 is taxed at 18%, the rest at 24% — exactly the same as someone in England. This catches a lot of Scottish investors out because many calculators silently use Scottish bands. This one doesn't — enter your actual income, the tool uses the right £50,270 threshold.

What "annual exempt amount" actually means

The AEA is per individual, per tax year, and use-it-or-lose-it. Any allowance you don't use by 5 April vanishes. It applies to total gains across all chargeable assets — not per asset. Married couples and civil partners each have their own £3,000, which means combined £6,000 of tax-free gains is available with a small amount of pre-disposal planning (a no-gain-no-loss spousal transfer first).

It used to be a lot bigger. As recently as 2022/23 the AEA was £12,300. It was cut to £6,000 in 2023/24, then halved again to £3,000 from 2024/25. That single change has made annual CGT planning — the kind this tool exists to do — far more relevant for ordinary investors. Many UK retail portfolios that comfortably fit under the old AEA now trigger CGT every time the holder rebalances.

Share matching rules — same-day, 30-day, section 104

If you hold multiple lots of the same security, HMRC doesn't let you cherry-pick which lot you're selling. Instead, three rules apply in strict order:

1. Same-day rule. Any sale is first matched against any acquisition of the same security on the same day, in the same account.
2. 30-day "bed and breakfast" rule. Then matched against acquisitions in the next 30 days (used to stop investors crystallising losses and immediately rebuying). The match is at the rebuy price.
3. Section 104 pool. Anything still unmatched uses the average cost of all your remaining holdings — the section 104 holding.

The 30-day rule does not apply if the rebuy is in an ISA, SIPP, or spouse's name — those are treated as different beneficial owners. That's why Bed-and-ISA still works, and why a spousal transfer doesn't trigger the rule either.

Losses — claim them, even small ones

Capital losses must be formally claimed (via Self Assessment, by the fourth anniversary of the end of the tax year they arose). Once claimed, they offset current-year gains before the AEA, then carry forward indefinitely. A common UK planning trick: realise gains up to the AEA and a loss in the same year that would otherwise be wasted — you keep more of next year's AEA intact because losses can only be carried forward, not back.

Bed-and-spouse — the doubled allowance

Inter-spouse transfers are no-gain-no-loss for CGT. The receiving spouse takes on your cost basis as if they'd always owned the holding, then can dispose of it using their own £3,000 AEA and own basic-rate band. For a higher-rate-taxpayer married to a basic-rate spouse, this can mean an extra £3,000 of tax-free gains and the rest taxed at 18% instead of 24%. The tool's spouse toggle just doubles the allowance — the band logic stays with you. For a proper split, model two separate scenarios.

When CGT planning matters most

• Late March every year — the AEA expires at 23:59 on 5 April. Use it or lose it.
• Before retirement — staging large unwrapped portfolios into ISAs/SIPPs over multiple years dramatically cuts lifetime CGT.
• Emigration — leaving the UK doesn't crystallise gains automatically, but timing matters and rebasing rules differ by destination country.
• Inheritance — death rebases the cost basis, so heirs inherit gains at market value. Disposing of standing gains before death typically wastes the rebase.
• Selling a business — BADR (Business Asset Disposal Relief) needs 24 months' qualifying ownership before disposal. Plan early.

Most retail investors only think about CGT once or twice a year. This tool is built so the planning takes 10 minutes, the result is saved, and you can re-open it next March exactly where you left off.