Guide
Capital Gains Tax when you sell a business (2026/27)
Updated
Three numbers decide the bill: your gain, whether the relief applies, and how much of the £1,000,000 lifetime limit you have left. Everything else is detail.
Working out the gain
- Start with the consideration for your shares or your share of the business.
- Deduct the base cost: what you originally paid for them.
- Deduct incidental costs of disposal, including broker, legal and accountancy fees on the sale.
- Deduct any allowable capital losses, including losses brought forward from earlier years.
- Deduct the annual exempt amount, £3,000 for 2026/27, against the gains charged at the highest rate first.
The rates that apply to what is left
- 18%
- Gains qualifying for Business Asset Disposal Relief or Investors' Relief, disposed of from 6 April 2026. Also the rate a basic rate taxpayer pays on other gains inside their unused basic rate band.
- 24%
- Other gains for a higher or additional rate taxpayer from 6 April 2026, including anything above the £1,000,000 relief limit.
- £3,000
- The annual exempt amount for individuals for 2026 to 2027, the same as 2025 to 2026 and 2024 to 2025. HMRC's published table is the place to check it each April.
All three figures are HMRC's, from the rates and allowances guidance last updated 13 April 2026 (gov.uk) and the relief guide itself (gov.uk).
Reporting and paying
A business or share sale is not UK residential property, so the 60-day property rules do not apply. You report it in the tax year after the disposal through Self Assessment, and if eligible you may instead use HMRC's real time Capital Gains Tax service to report by 31 December in the tax year after the sale (gov.uk). Put the tax aside on completion day; the bill arrives long after the money does.
Where the calculator will be wrong for you
- Earn-outs. The right to future consideration is itself an asset with its own tax treatment, and it is a common source of paying tax on money that never arrives.
- Loan notes and share-for-share deals. These can defer the gain rather than trigger it, sometimes at the cost of the relief.
- Option exercises. EMI and unapproved options interact with the two-year and 5% tests in ways a toggle cannot capture.
- More than one seller. Each shareholder has their own base cost, their own lifetime limit and their own income position.
- Losses and other gains in the same year. The order in which allowances and losses are set against different rate bands changes the total.
None of this is tax advice. It is a sourced starting point so that the conversation with your accountant begins somewhere near the right number.