# Corporation Tax Calculator

> Estimate your UK limited company's Corporation Tax with HMRC FY rates, marginal relief and per-financial-year apportionment.

Estimate your UK limited company's Corporation Tax liability, including marginal relief where augmented profits fall between the lower and upper limits.

Use the calculator: https://www.taxoptimiser.co.uk/calculators/corporation-tax

## Corporation Tax rates

From 1 April 2023 the main rate is 25%, charged where profits are above £250,000. A company with profits of £50,000 or less pays the small profits rate of 19%. Between the two limits the company pays the main rate less marginal relief. Before 1 April 2023 there was a single rate of 19%.

## How marginal relief works

Marginal relief is 3/200 of the difference between the upper limit and the company's augmented profits, multiplied by taxable profits over augmented profits. Augmented profits are taxable profits plus exempt dividends received from companies outside the group. The relief makes the bill rise gradually between the limits, so each extra pound of profit there is taxed at an effective 26.5%.

## Associated companies and short periods

The £50,000 and £250,000 limits are divided by the number of associated companies plus one, so a company with one associated company has limits of £25,000 and £125,000. The limits are also reduced in proportion for an accounting period shorter than 12 months.

## Periods that straddle 1 April

Corporation Tax rates are set for financial years running from 1 April to 31 March. Where an accounting period falls into two financial years, the profit is apportioned by days and each part is taxed at that year's rates. The calculator shows each financial year separately.

## Corporation Tax rates and limits

The limits are for a 12 month period and a company with no associated companies.

| Financial years | Main rate | Small profits rate | Lower limit | Upper limit | Marginal relief fraction |
| --- | --- | --- | --- | --- | --- |
| From 1 April 2023 | 25% | 19% | £50,000 | £250,000 | 3/200 |
| 1 April 2017 to 31 March 2023 | 19% | – | – | – | – |

## Corporation Tax on example profits

Worked through this calculator for the year to 31 March 2027, with no associated companies.

| Taxable profit | Corporation Tax | Marginal relief | Effective rate |
| --- | --- | --- | --- |
| £25,000 | £4,750.00 | £0.00 | 19% |
| £50,000 | £9,500.00 | £0.00 | 19% |
| £75,000 | £16,125.00 | £2,625.00 | 21.5% |
| £100,000 | £22,750.00 | £2,250.00 | 22.75% |
| £150,000 | £36,000.00 | £1,500.00 | 24% |
| £200,000 | £49,250.00 | £750.00 | 24.62% |
| £250,000 | £62,500.00 | £0.00 | 25% |
| £300,000 | £75,000.00 | £0.00 | 25% |

## Frequently asked questions

### How much Corporation Tax is due on £50,000 profit?

£9,500.00 for the year to 31 March 2027, for a company with no associated companies. That is an effective rate of 19%.

### How much Corporation Tax is due on £100,000 profit?

£22,750.00 for the year to 31 March 2027, for a company with no associated companies: the main rate less marginal relief of £2,250.00. That is an effective rate of 22.75%.

### What is the Corporation Tax rate for a small company?

A company with taxable profits of £50,000 or less pays the small profits rate of 19%. Above £250,000 the main rate of 25% applies to all the profit, and in between the company pays 25% less marginal relief.

### Who can claim marginal relief?

A UK resident company whose augmented profits are between £50,000 and £250,000 for a 12 month period. The limits are reduced for associated companies and for shorter periods. Close investment-holding companies cannot claim it.

### When is Corporation Tax due?

Nine months and one day after the end of the accounting period, for companies with taxable profits up to £1.5 million. The Company Tax Return (CT600) is due 12 months after the end of the period.

### Does this calculator replace a CT600?

No. It estimates the tax on a single profit figure. The Company Tax Return needs a full computation with adjustments such as capital allowances, disallowable expenses and losses, which Tax Optimiser prepares and files with HMRC.

## Related calculators

- [Corporation Tax Deadlines Calculator](https://www.taxoptimiser.co.uk/calculators/corporation-tax-deadlines.md): Payment, CT600 and Companies House dates for any accounting period.
- [Capital Allowances Calculator](https://www.taxoptimiser.co.uk/calculators/capital-allowances.md): Full expensing, AIA and car allowances on what your company has bought.
- [Loss Carry-Back Calculator](https://www.taxoptimiser.co.uk/calculators/loss-carry-back.md): Repayment from carrying a trading loss back, compared with carrying it forward.
- [Salary vs Dividend Calculator](https://www.taxoptimiser.co.uk/calculators/salary-vs-dividend.md): Find the salary and dividend mix that leaves a director with the most take-home pay.

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Last updated 4 October 2026. Guidance only: a general estimate, not tax advice. Published by Tax Optimiser, UK tax filing software (https://www.taxoptimiser.co.uk).