Corporation tax calculator
Updated
UK companies pay corporation tax at 19% on profits up to £50,000 and 25% above £250,000. In between, the main rate applies less marginal relief, which phases the rate up gradually. Both limits are shared between associated companies and cut for a period shorter than twelve months.
Not financial advice. General information using HMRC rates for the current tax year (2026-27); your position may differ.
Profits after allowable expenses and capital allowances, before corporation tax.
Other companies under common control, not counting this one. Each one divides both limits.
A shorter period cuts both limits in proportion. HMRC does this by days, so the answer here can differ by a few pounds.
Inside the marginal relief band each extra pound costs more than the main rate, because the relief tapers away.
Not financial advice. General information using HMRC rates for the 2026-27 tax year; your position may differ. Reviewed 30 October 2026.
Your profit
- Corporation tax£22,75023%
- Kept by the company£77,25077%
Tax as profits rise
The line steepens between the two limits, where marginal relief is withdrawn.
£87,500by profit 350000
Worked example
A company with taxable profits of £100,000 for a twelve-month period and no associated companies pays £22,750. Tax at the 25% main rate would be £25,000; marginal relief of 3/200 of the gap between £250,000 and the profits takes off £2,250. The effective rate is 22.8%. This is the example HMRC uses in its own guidance on marginal relief.
How it works
- Profits at or under the lower limit (£50,000) pay the small profits rate of 19%.
- Profits over the upper limit (£250,000) pay the main rate of 25% on every pound.
- In between, tax is worked out at 25% and marginal relief is taken off: 3/200 times the upper limit less the profits.
- Both limits are divided by one plus the number of associated companies, and reduced for a period shorter than twelve months.
Why the rate on the next pound is higher than the main rate
Marginal relief is largest when profits are just over the lower limit and shrinks to nothing at the upper limit. So as profits rise through the band, the company loses relief as well as paying the main rate. Each extra pound inside the band costs 26.5%, more than the main rate itself. The average rate still never goes above 25%; it is only the slice inside the band that is taxed harder. This is worth knowing when deciding the timing of a large expense or pension contribution, because a deduction that brings profits down inside the band saves tax at that higher marginal rate.
Associated companies
Two companies are associated if one controls the other or both are controlled by the same person or group. Each associated company divides the limits: with one associate, the lower limit becomes £25,000 and the upper limit £125,000. A company that has not traded at all in the period is ignored. Control by relatives and business partners can count, so the test is wider than it looks, and HMRC's guidance on associated companies is the place to check a real group.
Short accounting periods
A company's first period, or a period after a change of year end, is often shorter than twelve months. The limits are cut in proportion, so a six-month period has roughly half of each. HMRC apportions by days rather than months, which this page approximates with whole months. A period longer than twelve months is split into a twelve-month period and the remainder, each taxed separately.
When it is paid
Corporation tax is due nine months and one day after the end of the accounting period, and the return (CT600) twelve months after it. Very profitable companies pay by quarterly instalments instead. This page works out the tax only; it does not add interest, penalties, reliefs such as research and development, or losses brought forward.
Corporation tax rates in force
| Profits (12 months, no associates) | Rate | How it is worked out |
|---|---|---|
| Up to £50,000 | 19% | Small profits rate on all profits |
| £50,000 to £250,000 | 25% less marginal relief | Relief = 3/200 x (upper limit - profits) |
| Over £250,000 | 25% | Main rate on all profits |
Source: Finance Act 2021 s6, s7 and Sch 1 (CTA 2010 ss18A to 18N): small profits rate 19%, main rate 25%, marginal relief between 50,000 and 250,000 at a standard fraction of 3/200.
Want this worked out on your real numbers?
This page works on the figures you type. CoreFi can track your income, spending and tax position from the accounts you connect, on the same HMRC rates. It does not give tax advice.
Track your own numbersFrequently asked questions
What is marginal relief?
A reduction in corporation tax for companies with profits between £50,000 and £250,000. Tax is worked out at the 25% main rate and then 3/200 of the difference between the upper limit and the profits is taken off.
Do I need to claim marginal relief?
It is claimed on the company tax return (CT600), which works it out from the profits and the number of associated companies you enter. There is no separate application.
What counts as an associated company?
Broadly, another company that the same person or group controls, or that controls yours or is controlled by it. Dormant companies are ignored. The rules include control through relatives and partners, so check HMRC's guidance for a real group.
Does this include reliefs and losses?
No. Enter taxable profits after any losses, capital allowances and reliefs you are claiming. The page applies the rates and marginal relief to that figure.
Is this financial advice?
No. It is general information using HMRC rates for the current tax year, and your position may differ. For advice on your company, speak to an accountant.
More tax calculators
Not financial advice. This calculator gives general information using HMRC rates and thresholds for the 2026-27 tax year. It is not tax, legal or financial advice and does not take account of your circumstances; for advice, speak to a qualified accountant or tax adviser. CoreFi is a trading name of JG Core Ltd (company 16218779). Figures reviewed 30 October 2026.