UK Corporation Tax Calculator 2026/27
UK Corporation Tax calculator 2026/27 - 19% small profits rate to £50k, 26.5% marginal effective rate to £250k, 25% main rate above. Models the marginal relief formula and associated-company threshold split.
Three bands since 1 April 2023: 19% small profits rate to £50,000, an effective 26.5% marginal relief band from £50,001 to £250,000, then 25% main rate above. Models the Marginal Relief formula and the associated-companies threshold split. Verified against gov.uk CT rates.
Worked scenarios
- Small business £40,000 profit£7,600Effective 19.00%, marginal 19.0%
- Contractor £80,000 profit£17,450Effective 21.81%, marginal 26.5%
- Marginal band peak £200,000£49,250Effective 24.63%, marginal 26.5%
- Main rate £300,000 profit£75,000Effective 25.00%, marginal 25.0%
- 2 associated companies, £40k profit£8,725Effective 21.81%, marginal 26.5%
- 3 associated companies, £80k profit£19,950Effective 24.94%, marginal 26.5%
Next steps
Working out the tax is one half of the decision. These cover the other half.
Related calculators
Other UK tax calculators that pair with the Corp Tax.
Frequently asked questions
What is the UK Corporation Tax rate for 2026/27?
Three rates apply since 1 April 2023, all carried into 2026/27 unchanged: 19% Small Profits Rate on the first £50,000 of profit, a Marginal Relief band on £50,001-£250,000 (effective 26.5%), and 25% Main Rate above £250,000. The 26.5% in the marginal band is not a separate statutory rate - it's the effective tax on each extra pound of profit, falling out of the Marginal Relief formula (3/200 fraction × range above lower limit).
How does Marginal Relief work?
Marginal Relief reduces the headline 25% main-rate liability by an amount equal to (Upper Limit £250,000 - Augmented Profits) × (Profits / Augmented Profits) × 3/200. For a single company with no franked investment income, Augmented Profits = Profits, so the formula simplifies to (£250,000 - profits) × 3/200. Effective marginal rate on each pound between £50,001 and £250,000 is exactly 26.5%.
What are "associated companies"?
A company is "associated" if it is under common control (the same person or group of persons holds >50% of the share capital, voting rights, or distributable assets). Associated companies share the £50,000 and £250,000 thresholds proportionately - the thresholds are divided by (1 + number of associates). Two associated companies each face £25,000 / £125,000 effective thresholds, so the small profits rate band shrinks for each.
How does CT interact with contractor "salary + dividend" planning?
Limited company contractors operating outside IR35 typically take a £12,570 director salary (no Income Tax) and remaining profits as dividends. The dividends come from POST-CT profits - so the company pays Corporation Tax first (19% to £50k, 26.5% marginal, 25% above £250k), then the contractor pays Dividend Tax (10.75% basic / 35.75% higher / 39.35% additional) on the distributed amount. The contractor calculator at /contractor-calculator models the full sequence.
When was the 19% flat rate abolished?
Corporation Tax was a flat 19% from April 2017 to March 2023. The current banded structure (19% small profits + 25% main + marginal relief) replaced it from 1 April 2023, restoring a regime broadly similar to pre-2014. The 19% Small Profits Rate is preserved for the smallest businesses to limit the impact on contractor and SME profitability.
How are CT payments timed?
Standard "small company" payment is 9 months and 1 day after the end of the accounting period. "Large company" instalment payments apply to companies with profits above £1.5 million (£10 million for the largest) and require quarterly instalments. Most contractor and SME companies fall under the standard regime - file CT600 within 12 months of period end, pay tax within 9m+1d.