Corporation Tax calculator
Enter your company's taxable profit for the year. The calculator applies the small profits rate, the main rate or marginal relief, and shows your effective rate.
Corporation Tax due
£22,750
Main rate less marginal relief. Effective rate 22.75%.
- Taxable profit
- £100,000
- Tax at 25%
- £25,000
- Marginal relief3/200 of (£250,000 less profit)
- − £2,250
- Corporation Tax
- £22,750
- Profit after tax
- £77,250
Limits for this company: small profits rate up to £50,000, main rate from £250,000. Between the limits each extra pound of profit is taxed at 26.5%.
Figures used, 2026/27
- Small profits rate 19% up to £50,000
- Main rate 25% from £250,000
- Marginal relief fraction 3/200 between the limits
- 12-month accounting period; limits divided between associated companies
England, Wales and Northern Ireland. Rates reviewed . An estimate, not advice: your own position may differ.
How the calculator works
UK Corporation Tax has two rates. Profits up to 50,000 pounds are taxed at the small profits rate of 19%. Profits of 250,000 pounds or more are taxed at the main rate of 25%. Between those limits the main rate applies but marginal relief reduces the bill, so the effective rate climbs gradually from 19% to 25%.
Marginal relief is calculated as 3/200 of the difference between the upper limit and your profit. On profit of 100,000 pounds the relief is 2,250 pounds, giving tax of 22,750 pounds and an effective rate of 22.75%. Each extra pound of profit in this band is taxed at 26.5%, which is why it can be worth timing expenses or pension contributions carefully.
The limits are shared between associated companies. If your company is associated with one other, each company's limits halve to 25,000 and 125,000 pounds. The limits are also reduced proportionally for accounting periods shorter than 12 months. Enter the number of associated companies to see the adjusted limits.
Taxable profit is not the same as the profit in your accounts. Depreciation is added back and capital allowances deducted, some expenses are disallowed, and reliefs such as research and development can change the figure. Corporation Tax is normally due nine months and one day after the end of the accounting period, with the return filed within 12 months.
Frequently asked questions
19% on profits up to 50,000 pounds, 25% on profits of 250,000 pounds and above, and an effective rate between the two for profits in the middle thanks to marginal relief. The rates have been unchanged since April 2023.
Tax is first worked out at 25% on the whole profit. Relief of 3/200 of the difference between 250,000 pounds and the profit is then deducted. The result is an effective rate that rises smoothly from 19% at 50,000 pounds to 25% at 250,000 pounds.
Broadly, a company controlled by the same person or persons, including companies owned by close relatives in some circumstances. Dormant companies are ignored. Each associated company reduces the limits available to the others, so the count matters.
Nine months and one day after the end of your accounting period for most companies. The Company Tax Return (CT600) must be filed within 12 months of the period end. Large companies pay in quarterly instalments instead.
Usually close but not identical. The accounts show profit before tax under accounting rules; the tax computation adjusts that figure for disallowed expenses, capital allowances and reliefs. This calculator applies the rates to whatever taxable profit you enter.
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