Corporation Tax Calculator
Calculate your UK limited company corporation tax for 2025/26. Supports the small profits rate (19%), main rate (25%), and automatic marginal relief calculation for profits between £50,000 and £250,000.
This is an estimate only — always consult a qualified accountant for your CT600 filing.
Frequently asked questions
What are the UK corporation tax rates for 2025/26?
From April 2023 onwards, the UK has a two-rate corporation tax system. Companies with annual profits of £50,000 or less pay the small profits rate of 19%. Companies with profits above £250,000 pay the main rate of 25%. Companies with profits between £50,000 and £250,000 benefit from marginal relief, which gives an effective rate that tapers from 19% to 25%. These limits are divided by the number of associated companies plus one.
How does marginal relief work?
Marginal relief reduces the corporation tax liability for companies with profits between the small profits limit (£50,000) and the upper limit (£250,000). The formula is: Tax = Profits × 25% − Marginal Relief, where Marginal Relief = (Upper Limit − Profits) × 3/200. This means a company with £100,000 profit pays roughly 21.5% effective rate, while a company at £200,000 pays around 24%. The result is a smooth taper rather than a cliff edge.
When do I need to pay corporation tax?
Corporation tax is normally due 9 months and 1 day after the end of your accounting period. For example, if your accounting year ends on 31 March, your corporation tax is due by 1 January the following year. You must file a Company Tax Return (CT600) with HMRC within 12 months of the accounting period end. Large companies (profits over £1.5m) must pay in quarterly instalments.
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