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Corporation tax calculator

Work out corporation tax for a UK company, including marginal relief between £50,000 and £250,000 of profit, associated companies and short accounting periods.

£22,750.00Corporation tax

22.75%Effective rate

Rate band	Main rate with marginal relief
Lower limit for this company	£50,000
Upper limit for this company	£250,000
Tax at 25%	£25,000.00
Marginal relief	−£2,250.00
Corporation tax due	£22,750.00
Profit after tax	£77,250.00

Profits between the limits are taxed at an effective 26.5% on each extra pound (marginal rate), even though the average rate is lower.

Rates checked 24 October 2026 against GOV.UK corporation tax rates and HMRC marginal relief guidance. For guidance only, not tax or legal advice.

Corporation tax rates

Profits	Rate
Up to £50,000	19% (small profits rate)
£50,001 to £250,000	25%, reduced by marginal relief
Over £250,000	25% (main rate)

These rates have applied since 1 April 2023 and are already set for the financial years starting 1 April 2026 and 1 April 2027. The limits are for a 12-month accounting period with no associated companies.

How marginal relief works

Between the limits, you work out tax at 25% and then take off marginal relief:

Marginal relief = (upper limit − augmented profits) × (taxable profits ÷ augmented profits) × 3/200

Augmented profits are your taxable profits plus dividends received from companies outside your group. Without such dividends, the last part is 1.

Example. Taxable profits of £100,000 for 12 months, no associated companies. Tax at 25% is £25,000. Marginal relief is (£250,000 − £100,000) × 3/200 = £2,250. Corporation tax: £22,750, an average rate of 22.75%.

Each extra pound of profit between the limits is taxed at 26.5%, higher than the main rate. That matters when you plan salary, pension contributions or dividends.

Associated companies and short periods

If your company has associated companies (broadly, companies under the same control), the £50,000 and £250,000 limits are divided by the number of associated companies plus one. With one associated company, the limits are £25,000 and £125,000.

For an accounting period shorter than 12 months, the limits are reduced in proportion. HMRC does this by days; this calculator uses months as a close guide.

Deadlines

For most companies, corporation tax is due 9 months and 1 day after the end of the accounting period. The Company Tax Return (CT600) is due 12 months after the end of the period. Large companies pay in quarterly instalments.

Corporation tax calculator questions

What is the corporation tax rate for 2026/27?

19% on profits up to £50,000, 25% on profits over £250,000, and 25% with marginal relief in between. These rates apply for the financial year starting 1 April 2026.

How much corporation tax do I pay on £100,000 profit?

£22,750 for a 12-month period with no associated companies: £25,000 at 25% less £2,250 of marginal relief.

What is the marginal rate of corporation tax?

26.5% on each pound of profit between £50,000 and £250,000, because marginal relief tapers away as profits rise.

What counts as an associated company?

Broadly, another company that controls yours, that yours controls, or that is under the same control. Dormant companies and some passive holding companies are left out. See HMRC’s guidance for the detail.

When is corporation tax due?

Usually 9 months and 1 day after the end of your accounting period, with the CT600 return due 12 months after the period ends.

Sources

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