Corporation Tax Calculator UK 2025/26
Corporation Tax Calculator – Use our free Corporation Tax Calculator to work out how much tax your company will pay for the 2025/26 financial year.
Simply enter your taxable profits, accounting period length, and associated companies to instantly calculate your estimated corporation tax liability.
Corporation Tax Calculator
Enter your company’s taxable total profits, number of associated companies, and accounting period length to calculate your corporation tax.
UK Corporation Tax Calculator
Why use a Corporation Tax Calculator?
Corporation tax can be complex, especially since April 2023 when the UK reintroduced different corporation tax rates and marginal relief. Small companies may still benefit from the 19% small profits rate, while larger companies face the 25% main rate. Businesses in between benefit from Marginal Relief, which reduces the effective rate.
Our calculator helps you:
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Quickly estimate corporation tax due on profits
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Understand how the small profits rate, main rate, and marginal relief apply
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Factor in short accounting periods and associated companies
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Plan for cash flow by knowing your expected tax bill
How Corporation Tax Works in the UK
For the financial year 2025/26:
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Small profits rate: 19% (profits up to £50,000)
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Main rate: 25% (profits above £250,000)
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Marginal Relief: Applies between £50,000 and £250,000, gradually increasing the effective tax rate
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Adjustments: Both thresholds are reduced if your accounting period is shorter than 12 months or if you have associated companies
These rules apply to most limited companies in the UK.
Example Calculation
A company with:
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Profits of £120,000
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A 12-month accounting period
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No associated companies
…will fall into the marginal relief band. Our Corporation Tax Calculator shows the main rate tax due, marginal relief applied, and the final corporation tax liability, along with the effective tax rate.
Who should use this Corporation Tax Calculator tool?
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Small business owners running UK limited companies
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Company directors planning cash flow
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Startups forecasting future profits and tax bills
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Accountants and finance teams checking quick estimates before final computations
Important Notes
This Corporation Tax Calculator is a guide only. It does not cover:
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R&D tax relief or creative industry reliefs
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Special rules for “ring fence” profits (oil & gas companies)
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Quarterly instalment payment rules for very large companies
Always consult a qualified accountant for tailored tax planning.
For further reading why not take a look at our other hand Calculators
Dividend Tax Calculator FAQ
What is Corporation Tax?
Corporation Tax is a tax that UK limited companies pay on their taxable profits, including trading profits, investments, and chargeable gains.
What are the Corporation Tax rates in 2025/2026?
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19% for profits up to £50,000
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25% for profits above £250,000
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Marginal Relief applies between these limits
How does Marginal Relief work?
Marginal Relief gradually increases the effective tax rate between the small profits rate and the main rate, so companies with profits between £50,000 and £250,000 pay a tapered rate instead of jumping straight to 25%
What are associated Companies and why do they matter?
If your company controls or is controlled by another company, they are classed as associated companies. The £50,000 and £250,000 thresholds are divided between the total number of associated companies, reducing the limits for each.
How do short accounting periods affect corporation tax?
If your company’s accounting period is less than 12 months, the thresholds (£50,000 and £250,000) are proportionally reduced.
When is Corporation Tax due?
Corporation Tax is normally due 9 months and 1 day after the end of your company’s accounting period. Very large companies may have to pay by quarterly instalments.
Do all companies pay the same rates?
Most do, but companies with “ring fence” profits (e.g. oil and gas companies) pay different rates. Some reliefs and exemptions may also reduce your effective tax bill.
Can I reduce my corporation tax bill legally?
Yes, by claiming allowable expenses, capital allowances, R&D tax credits, or pension contributions. Planning dividends and salaries effectively can also reduce overall tax liabilities.
Why use a Corporation Tax Calculator?
Because the mix of rates, allowances, marginal relief, and adjustments for associated companies can be complicated. A calculator gives you a clear estimate in seconds, helping with planning and budgeting.