Free Corporation Tax Calculator
Work out your UK Corporation Tax in seconds. Enter your company's taxable profit and accounting period to see the tax due — including the 19% small profits rate, the 25% main rate, and marginal relief in between.
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Corporation Tax due
£22,750.00
For £100,000 of taxable profit from 1 April 2026 to 31 March 2027, with no associated companies.
- Effective rate
- 22.75%
- Rate band
- Marginal relief
- Period length
- 365 days (full limits)
Tax at main rate £25,000.00 - marginal relief £2,250.00 = £22,750.00.
Limits used: lower £50,000.00, upper £250,000.00.
Estimate only, for a non-ring-fence UK company in financial years 2023–2026 (rates unchanged). It excludes reliefs and adjustments such as capital allowances, R&D, brought-forward losses and franked investment income. For your exact figure — and to actually file — start a return.
How is UK Corporation Tax calculated?
Corporation Tax is charged on your company's taxable profit for the accounting period: 19% (the small profits rate) on profits up to £50,000, 25% (the main rate) above £250,000, and 25% less marginal relief in between. Both limits are shared between associated companies and reduced for accounting periods shorter than 12 months.
In short, UK Corporation Tax has three bands for company profits:
| Taxable profit | Rate |
|---|---|
| Up to £50,000 (the lower limit) | 19% — small profits rate |
| £50,000 to £250,000 | 25% less marginal relief |
| Over £250,000 (the upper limit) | 25% — main rate |
In the middle band you pay the 25% main rate reduced by marginal relief, which produces an effective rate that rises smoothly from 19% toward 25%. Marginal relief is the standard fraction of 3/200 multiplied by the gap between your profits and the upper limit. Our guide to Corporation Tax rates and marginal relief walks through the formula with worked examples.
Two things change the limits: the £50,000 and £250,000 thresholds are divided between associated companies (companies under common control), and they are reduced for accounting periods shorter than 12 months. This calculator applies both automatically.
Remember the calculator works from your taxable profit — the figure after tax adjustments such as add-backs for depreciation, capital allowances and disallowable costs. See what a CT600 is and how to file one, and the payment and filing deadlines.
How much Corporation Tax is due on £40,000, £120,000 or £300,000 of profit?
Worked examples for a 12-month accounting period in financial year 2026 (1 April 2026 to 31 March 2027), for a company with no associated companies: £40,000 of taxable profit pays £7,600 at the 19% small profits rate, £120,000 pays £28,050 after marginal relief and £300,000 pays £75,000 at the 25% main rate.
| Taxable profit | How it is worked out | Corporation Tax | Effective rate |
|---|---|---|---|
| £40,000 | £40,000 × 19% small profits rate | £7,600 | 19% |
| £120,000 | £120,000 × 25% = £30,000, minus marginal relief of 3/200 × (£250,000 − £120,000) = £1,950 | £28,050 | 23.4% |
| £300,000 | £300,000 × 25% main rate | £75,000 | 25% |
Rates and limits are those published on GOV.UK in Corporation Tax rates and allowances.
Frequently asked questions
What profit figure should I enter in the calculator?
Enter your company's taxable profit for the accounting period, in pounds: the figure after tax adjustments such as add-backs for depreciation, capital allowances and disallowable costs, rather than the profit shown in your accounts. You can type it as 100,000 or £100,000.
What is marginal relief?
Marginal relief eases the jump from 19% to 25% for profits between £50,000 and £250,000. It is calculated as the standard fraction (3/200) × (upper limit − augmented profits) × (taxable profits ÷ augmented profits), and is deducted from the tax charged at the main rate, giving an effective rate between 19% and 25%.
What are the current Corporation Tax rates?
For financial years 2023 to 2026 the main rate is 25%, the small profits rate is 19%, the lower limit is £50,000, the upper limit is £250,000 and the marginal relief standard fraction is 3/200. Always confirm the current figures on GOV.UK before filing.
How do associated companies affect the calculation?
The £50,000 and £250,000 limits are divided by the number of associated companies plus one. For example, with one associated company the limits halve to £25,000 and £125,000, so marginal relief and the main rate start at lower profit levels.
What if my accounting period is shorter than 12 months?
The lower and upper limits are reduced in proportion to the length of the period (on a 365-day basis), so a six-month period uses roughly half the limits. A full 12-month period keeps the full limits. This calculator applies that automatically from the dates you enter.
Can I file my return with this figure?
This is an estimate for a straightforward non-ring-fence company and excludes reliefs and adjustments such as capital allowances, R&D, losses and franked investment income. For the exact figure and to actually file your CT600 and accounts, prepare your return with Taxley.
When do I pay and file my Corporation Tax?
You must pay within 9 months and 1 day of the end of your accounting period, and file your Company Tax Return (CT600) within 12 months. The payment deadline falls before the filing deadline.
From estimate to filed return
Taxley turns your figures into a complete CT600, iXBRL accounts and computations — ready to file with HMRC. Free to prepare and preview; pay only when you file.
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