UK Corporation Tax Calculator 2026/27

Worked scenarios

• Small business £40,000 profit
  £7,600
  Effective 19.00%, marginal 19.0%
• Contractor £80,000 profit
  £17,450
  Effective 21.81%, marginal 26.5%
• Marginal band peak £200,000
  £49,250
  Effective 24.63%, marginal 26.5%
• Main rate £300,000 profit
  £75,000
  Effective 25.00%, marginal 25.0%
• 2 associated companies, £40k profit
  £8,725
  Effective 21.81%, marginal 26.5%
• 3 associated companies, £80k profit
  £19,950
  Effective 24.94%, marginal 26.5%

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 (8.75% basic / 33.75% 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.