Business sale tax calculator

It follows HMRC's steps for working out Capital Gains Tax on a sale of shares, using the rates for sales between 6 April 2026 and 5 April 2027.

1. The gain. The sale price, less the costs of selling and what you paid for the shares.
2. The tax-free allowance. Everyone has £3,000 a year. It comes off the part of the gain that would be taxed at the highest rate.
3. The relief. If you qualify, gains up to what's left of your £1,000,000 lifetime limit are taxed at 18%. They use up your basic rate band first.
4. Everything else. Gains above the limit, or the whole gain without the relief, are taxed at 18% in whatever is left of your basic rate band and 24% above it.
5. Your basic rate band. It's £37,700 of income after your £12,570 Personal Allowance. Your other income uses it up first, so with other income of £50,270 or more there's none left for gains.

If your husband, wife or civil partner owns some of the shares, the gain is split in line with your shares and each of you is worked out separately, with your own allowance, band and lifetime limit.

The relief is worth less than it was. Now the rate is 18%, the same as the basic rate, it saves6p in every pound of gain that would otherwise be taxed at 24%. For one person, that's £60,000 at most.

Checked on GOV.UK on 28 October 2026, after the Budget on 28 October 2026. The Budget cut the lifetime limit to £500,000 for sales from 6 April 2027; the other rates here don't change. Our before and after calculator shows the difference on your gain.

• Whether you qualify. The relief has conditions that have to be met for the two years before the sale. Our guide to Business Asset Disposal Relief covers them.
• Payments made later. A fixed sum paid later usually counts at the time of the sale, so tax can be due before the money arrives. Earn-outs and shares in the buyer are taxed differently.
• Selling the business rather than your shares. If your company sells the business and its assets, the company usually pays Corporation Tax, and you pay tax again when you take the money out.
• Losses, other gains and Income Tax reliefs in the same tax year, which can all change the figure.
• How you each came to own your shares. The calculator splits what you paid in line with your shares, which may not match what each of you paid.
• The date of the sale. The date that counts is usually when an unconditional contract is made, which can be before completion.