Guide · Updated February 2026
UK Corporation Tax Rates and How to Calculate Your Bill (2025/26)
Corporation tax in the UK is not a flat rate. Since April 2023, there are two rates and a marginal relief band in between. Here is how to work out what your company owes.
The rates for 2025/26
| Taxable profits | Rate | Name |
|---|---|---|
| Up to £50,000 | 19% | Small profits rate |
| £50,001 – £249,999 | Between 19% and 25% | Marginal relief band |
| £250,000 and above | 25% | Main rate |
These thresholds are divided by the number of associated companies (plus one). If your company has one associated company, the small profits threshold drops to £25,000 and the upper limit to £125,000.
How marginal relief works
If your profits fall between £50,000 and £250,000, you pay the main rate (25%) but get marginal relief that reduces your effective rate. The formula is:
The fraction 3/200 is the standard fraction set by HMRC. The effective tax rate rises gradually from 19% at £50,000 to 25% at £250,000. At around £120,000 of profit, the effective rate is roughly 22%.
Quick examples
Profit: £30,000
Below the small profits threshold. Tax = £30,000 × 19% = £5,700
Profit: £100,000
In the marginal relief band. Tax at main rate = £25,000. Marginal relief = (£250,000 − £100,000) × £100,000/£250,000 × 3/200 = £900. Final tax = £25,000 − £900 = £24,100 (effective rate ~24.1%)
Profit: £500,000
Above the upper limit. Tax = £500,000 × 25% = £125,000
Try the calculator
Enter your taxable profit to see your corporation tax bill, effective rate, and marginal relief. Adjust for associated companies if applicable.
Corporation Tax Calculator
These calculations are estimates based on published HMRC rates and thresholds for the current tax year. They do not constitute tax advice. Your actual tax liability may differ.
Deductible expenses
Your taxable profit is revenue minus allowable expenses. Common deductions for small companies include office rent, equipment, software subscriptions, professional services, travel, staff costs, and pension contributions. Capital expenditure (computers, vehicles) is usually claimed through capital allowances rather than deducted directly. The Annual Investment Allowance lets you claim up to £1 million of capital expenditure in the year of purchase.
When is corporation tax due?
- •Payment: 9 months and 1 day after the end of your accounting period
- •CT600 filing: 12 months after the end of your accounting period
Note that you must pay before you file. Late payment incurs interest from the due date. Late filing attracts a flat £100 penalty, rising to £200 after 3 months and further penalties after that.
Calculate and file with Taxentis
Taxentis calculates your corporation tax automatically — including marginal relief — and files your CT600 directly to HMRC. Enter your company's profit and loss figures and let us handle the maths and the submission.