UK Corporation Tax Calculator 2026
Calculate corporation tax on company profits, including the small profits rate, main rate and marginal relief between £50,000 and £250,000.
| Rate band | — |
|---|---|
| Tax at 25% main rate | — |
| Marginal relief | — |
| Effective rate | — |
| Profit after tax | — |
In short
UK corporation tax is 19% on profits up to £50,000 and 25% on profits of £250,000 or more. Between those limits, marginal relief of 3/200 × (£250,000 − profit) is deducted from the 25% charge, giving an effective marginal rate of 26.5%. Limits are shared between associated companies.
Who this is for: UK company owners and bookkeepers estimating corporation tax including marginal relief.
19%, 25% and the marginal relief band
Since April 2023: profits up to £50,000 pay the small profits rate of 19%; profits of £250,000 or more pay the main rate of 25%. Between the two, you pay 25% less marginal relief of 3/200 × (£250,000 − profit), which produces an effective marginal rate of 26.5% on each pound in that band.
Both limits are divided by the number of associated companies and pro-rated for accounting periods shorter than 12 months — which is why a small group can lose the 19% rate quickly.
See also: UK Dividend Tax Calculator 2026/27, UK VAT Calculator.
Assumptions
- 19% up to £50,000; 25% at £250,000 and above; marginal relief of 3/200 × (upper limit − profit) between.
- Limits are divided by the number of associated companies and pro-rated for periods under 12 months.
- Augmented profits, losses and reliefs are not modelled.
Worked example
25% × 120,000 = £30,000; marginal relief 3/200 × (250,000 − 120,000) = £1,950 → £28,050 (effective 23.4%).
Frequently asked questions
Is dividend income from other companies counted?
Exempt distributions are added to profits when testing the limits (as 'augmented profits') but not taxed — this tool ignores them.
When is corporation tax due?
Nine months and one day after the end of the accounting period for most companies; large companies pay by quarterly instalments.
Do losses carry forward?
Yes — trading losses can be set against future profits (with restrictions above £5m), reducing the taxable figure you enter here.
How much corporation tax on £100,000 profit?
£22,750 — 25% less marginal relief of £2,250 — an effective rate of 22.75%.
Does a dormant subsidiary count as an associated company?
Dormant companies are ignored, but active associated companies reduce the £50,000 and £250,000 limits for each company.
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