Free Tool

UK Corporation Tax Calculator

Estimate Corporation Tax at 19%, 25% or with marginal relief, including associated companies and short periods.

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Added to taxable profits to give “augmented profits”, which set the rate band.

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UK Corporation Tax Rates

The Marginal Relief Formula

Tax = 25% × profits − 3/200 × (upper limit − augmented profits) × (profits ÷ augmented profits)

The limits are divided by 1 + the number of associated companies and reduced proportionately for accounting periods shorter than 12 months. Augmented profits are taxable profits plus most dividends received from non-group companies.

Deadlines

Corporation Tax is normally payable 9 months and 1 day after the end of the accounting period; the CT600 return is due 12 months after it ends.

A live Corporation Tax provision, all year

ETaxFlow computes 19%/25% and marginal relief as you post.

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Frequently Asked Questions

19% on profits up to £50,000 and 25% on profits above £250,000, with marginal relief in between.

For profits between the limits you pay 25% and then deduct 3/200 × (upper limit − augmented profits) × (profits ÷ augmented profits), so the effective rate rises smoothly from 19% to 25%.

Yes. Both limits are divided by one plus the number of associated companies, and reduced for accounting periods under 12 months.

Taxable profits plus most dividends received from non-group companies. They decide which rate band applies, though tax is charged on taxable profits.

No. It estimates the tax. ETaxFlow computes Corporation Tax from your accounts and exports a workpaper for your accountant to file the CT600 with HMRC.

UK Guides & Resources

Go deeper on the rules behind the numbers

Guide
UK Corporation Tax Guide
19%, 25%, marginal relief and deadlines explained.
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