Corporation Tax Calculator FY2026
Work out your limited company's corporation tax for an accounting period in FY2026 — 1 April 2026 to 31 March 2027. Small profits rate, main rate and marginal relief, with the associated companies divisor applied properly.
Company profits
FY2026 runs 1 April 2026 to 31 March 2027. The 19% and 25% rates and the £50,000 / £250,000 limits are identical in both financial years.
Company turnover less cost of sales
Salaries, employer NIC, office, software, professional fees
Capital allowances, employer pension contributions actually paid, trading losses brought forward
Count the other companies, not this one. Both limits are divided by 1 + this number, so one associated company halves them to £25,000 and £125,000.
Dividends from companies outside your group. Added to profits to give augmented profits, which decide the band — tax is still charged only on your own profits.
Leave at 365 for a full year. Shorter periods pro-rate both limits by days ÷ 365.
Corporation tax: £85,000 × 25% − £2,475.00 = £18,775.00
| Item | Amount |
|---|
| Item | FY2026 | FY2025 |
|---|---|---|
| Small profits rate — augmented profits under £50,000 | 19% | 19% |
| Main rate — augmented profits over £250,000 | 25% | 25% |
| Marginal relief lower limit | £50,000 | £50,000 |
| Marginal relief upper limit | £250,000 | £250,000 |
| Standard marginal relief fraction | 3/200 | 3/200 |
| Effective marginal rate inside the band | 26.5% | 26.5% |
| Unit trusts and open-ended investment companies | 20% | 20% |
| Ring fence: small profits / main / fraction | 19% / 30% / 11⁄400 | 19% / 30% / 11⁄400 |
A financial year. Corporation tax rates are set for a financial year running 1 April to 31 March: FY2026 is 1 April 2026 to 31 March 2027. The 6 April to 5 April tax year — 2026/27 — is an income tax and National Insurance concept and does not apply to company profits.
Your company is charged on its own accounting period, and the rate for that period comes from the financial year (or years) it falls in. Because the 19% and 25% rates and the £50,000 / £250,000 limits are identical for FY2025, FY2026 and FY2027, a period straddling 1 April needs no apportionment between financial years.
Between the £50,000 lower limit and the £250,000 upper limit of augmented profits, marginal relief tapers the 25% main rate back towards 19%:
Marginal relief = 3/200 × (upper limit − augmented profits) × (taxable total profits ÷ augmented profits), and corporation tax = taxable total profits × 25% − marginal relief.
Augmented profits are your taxable total profits plus exempt distributions received from companies outside your group. The relief is charged on your taxable profits only — the augmented figure just decides which band you land in and how much relief you get.
26.5%. The marginal relief fraction 3/200 is 1.5 percentage points, and the relief is withdrawn as profits rise, so every extra pound of profit inside the band costs 25% + 1.5% = 26.5% in corporation tax.
That is the rate on the next pound. The effective rate — tax as a percentage of all your profits — climbs smoothly from 19% at £50,000 to 25% at £250,000, with no cliff edge at either limit.
19%, where augmented profits are £50,000 or less. The limit is divided by 1 + the number of associated companies, so with one associated company the small profits rate stops at £25,000.
There is no small profits rate and no marginal relief for a close investment-holding company, or where the company has ring fence profits — those run on their own rates.
Both limits are divided by 1 + the number of associated companies. One associated company gives limits of £25,000 and £125,000; two gives £16,667 and £83,333. Profits that looked like small-profits-rate profits can end up in the marginal band, or straight onto the 25% main rate.
This is the single most common reason a corporation tax estimate comes out wrong, which is why the field sits open above. Broadly, another company counts as associated if one company controls the other, or both are under the control of the same person or persons, at any time in the accounting period — the tests are detailed, so if you hold more than one company have it checked. See GOV.UK corporation tax rates.
Costs incurred wholly and exclusively for the trade: salaries and employer NIC, office and software, business travel, professional fees, equipment. Not everything a company pays for is deductible — client entertaining is the classic example that is not.
Employer pension contributions are relieved in the period they are actually paid, not accrued, so a contribution made after the year end lands in the following period.
Usually 9 months and 1 day after the end of the accounting period. For a 12-month period ending 31 March 2027, payment is due by 1 January 2028 — and the CT600 return itself is due 12 months after the period end. Large companies pay in quarterly instalments instead.
No. This calculator provides arithmetic estimates for illustration only. Always consult a qualified accountant for advice on your specific situation.
About corporation tax in FY2026
Corporation tax is charged on your limited company's profits for an accounting period, and the rates come from the financial year — 1 April to 31 March — that the period falls in. FY2026 runs from 1 April 2026 to 31 March 2027. That is not the same span as the 2026/27 tax year, which starts on 6 April and governs your personal income tax and National Insurance instead.
Nothing moved at April 2026. The small profits rate is 19%, the main rate is 25%, the marginal relief limits are £50,000 and £250,000, and the standard fraction is 3/200. Finance Act 2026 holds the same rates and limits for FY2027 too, so where an accounting period straddles 1 April — a 31 December or 30 June year end, say — apportioning the profit between the two financial years makes no difference to the answer.
The marginal relief formula
With N as taxable total profits, A as augmented profits (N plus exempt distributions received from companies outside your group), L as the lower limit and U as the upper limit:
- A ≤ L → corporation tax = N × 19%
- A > U → corporation tax = N × 25%
- L < A ≤ U → marginal relief = 3/200 × (U − A) × (N ÷ A), and corporation tax = N × 25% − marginal relief
The limits are divided by 1 + the number of associated companies, then multiplied by days ÷ 365 where the accounting period is shorter than 12 months. Note that it is augmented profits that decide the band, while the tax itself is charged on your taxable profits — which is why the (N ÷ A) factor is in the formula at all.
Worked example — with an exempt distribution
Taxable total profits of £90,000 and £8,000 of exempt distributions from a non-group company give augmented profits of £98,000. Tax at the main rate is £90,000 × 25% = £22,500. Marginal relief is 3/200 × (£250,000 − £98,000) × (£90,000 ÷ £98,000) = £2,094. Corporation tax is therefore £20,406 — an effective rate of 22.67% on the £90,000 actually taxed.
Why 26.5% matters more than the effective rate
Inside the marginal band each additional pound of profit is taxed at 26.5% — higher than the 25% main rate, because you lose relief as you go. That is the number to use when you are deciding whether to bring a cost forward, pay an employer pension contribution before the year end, or take profit as salary rather than leave it in the company. The effective rate on the whole profit is always lower, somewhere between 19% and 25%.
For more on running a limited company and contractor accounting, see our guides. HMRC's own rate tables are at GOV.UK corporation tax rates.
Corporation tax is charged by financial year, not by tax year. This calculator provides arithmetic calculations only. Verify with HMRC guidance or a qualified accountant.