Corporation Tax Calculator 2026/27

There are two main rates: 19% for companies with profits up to £50,000 (small profits rate), and 25% for profits over £250,000 (main rate). Companies with profits between £50,000 and £250,000 benefit from marginal relief, producing an effective rate between 19% and 25%.

Marginal relief tapers the corporation tax bill for profits between the lower limit (£50,000) and upper limit (£250,000). The formula is: tax = profits × 25% − (3/200) × (upper limit − profits). Within this band the marginal rate on each extra £1 of profit is 26.5%.

The £50,000 and £250,000 profit limits are divided equally by the total number of associated companies. Two associated companies halve both thresholds to £25,000 and £125,000. Association broadly means common control: a holding company and its subsidiaries are associated, as are sibling companies under the same controlling shareholder.

For companies with annual profits under £1.5m, payment is due 9 months and 1 day after the accounting period end. The CT600 tax return must be filed online within 12 months. Large companies (profits over £1.5m) pay in quarterly instalments.

Yes. Common reliefs include: salary and employer pension contributions, capital allowances (Annual Investment Allowance up to £1m), R&D tax relief, business mileage, professional subscriptions, and all genuine trading expenses. Timing expenses strategically and maximising pension contributions are effective and legitimate planning tools.