Calculator
UK Corporation Tax Estimator
Estimate your UK company's Corporation Tax, including marginal relief. Profits up to the lower limit are taxed at the small-profits rate, profits above the upper limit at the main rate, and profits in between are tapered by marginal relief. Enter your taxable profit to see the figure and your effective rate.
Estimate your UK Corporation Tax
Enter your company’s taxable profit for the year. This uses the 2025/26 rates, including marginal relief between the lower and upper limits.
Estimated Corporation Tax
£0
How the rate works
- Profits up to £50,000: small-profits rate (19%).
- Profits over £250,000: main rate (25%).
- In between: main rate tapered down by marginal relief.
Indicative only, for a single standalone company on 2025/26 rates. The limits are shared between associated companies and short/long accounting periods adjust them — and for a US owner, the same profit can also face US tax under the GILTI/NCTI rules. We model both sides.
Own a UK company as a US citizen?
UK Corporation Tax is only half the picture — the same profits can trigger US tax under GILTI/NCTI. We coordinate both so you don’t overpay. The first consultation is free.
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Frequently asked questions
It depends on your profit level. Profits up to the lower limit are taxed at the small-profits rate, profits above the upper limit at the main rate, and profits in between are taxed at the main rate reduced by marginal relief — so the effective rate rises gradually across that band rather than jumping.
Marginal relief smooths the transition between the small-profits rate and the main rate. For profits between the lower and upper limits, you start from the main rate and subtract a relief amount, which means your effective rate sits somewhere between the two headline rates. It prevents a sudden cliff-edge as profits grow.
Yes. The lower and upper limits are divided by the number of associated companies, so a group of companies reaches the main rate at lower individual profit levels. This calculator assumes a single standalone company, so if you control other companies the thresholds will be lower than shown.
Often, yes. A UK company owned by a US citizen is usually a controlled foreign corporation, so its profits can be taxed in the US under the GILTI/NCTI rules even before they are distributed — with the UK Corporation Tax generally available as a credit. The two systems need to be coordinated to avoid overpaying.
Own a UK company as a US citizen?
UK Corporation Tax is only half the picture — we coordinate it with the US GILTI/NCTI rules so you don't overpay.