Corporation Tax Calculator 2025/26
Calculate UK corporation tax with marginal relief, see the effective rate on your profits, and compare salary vs dividends extraction for director-shareholders. 2025/26 HMRC rates.
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How to Use This Calculator
Corporation Tax tab
The default tab. Enter your company's taxable profit (profit before corporation tax) and the number of associated companies. The calculator shows whether you pay the small profits rate (19%), main rate (25%), or qualify for marginal relief. Expand "More options" to include capital allowances (AIA) and R&D tax relief.
Marginal Relief Explained tab
See exactly how the effective corporation tax rate changes between £50,000 and £250,000. Enter any profit figure and see the precise effective rate, the marginal relief amount, and a rate progression table. Useful for understanding why earning slightly more can push you into a higher effective bracket.
Tax Planning tab
For director-shareholders deciding how to extract money from their company. Compare taking all income as salary versus the optimal salary+dividends strategy. Enter your company revenue, expenses, and director salary. The calculator shows corporation tax, employer NI, employee NI, income tax, dividend tax, and total take-home for each strategy.
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Every input is encoded in the URL. Click Share to send your exact scenario to an accountant, business partner, or co-director.
The Formula
Corporation tax uses a two-rate system with marginal relief in between:
Corporation Tax = Profit × 19%
If profit ≥ £250,000:
Corporation Tax = Profit × 25%
If £50,000 < profit < £250,000:
Corporation Tax = (Profit × 25%) − Marginal Relief
Marginal Relief = 3/200 × (£250,000 − Profit)
Both the £50,000 and £250,000 thresholds are divided by the number of associated companies plus one. For example, if you have 1 associated company, the limits become £25,000 and £125,000.
Between the two thresholds, the effective marginal rate on each additional pound of profit is 26.5%, not 25%. This is because you lose 1.5p of marginal relief for every extra pound earned (3/200 = 1.5%).
Example
James — Software Consultancy, Manchester
James runs a limited company with £150,000 taxable profit for the year ending 31 March 2026. He has no associated companies.
Corporation Tax Calculation
Tax Planning: Salary + Dividends
James pays himself a salary of £12,570 (personal allowance) and takes the rest as dividends:
James must file his CT600 by 31 March 2027 (12 months after period end) and pay the £36,000 by 1 January 2027 (9 months and 1 day after period end).