UK Corporation Tax Calculator

Calculate UK Corporation Tax for 2026 including marginal relief, R&D tax credits, and associated company rules. Updated for HMRC 2025/26 rates.
✅ Last verified: June 2026 — HMRC Corporation Tax rates 19%/25% confirmed unchanged for 2026/27

Small Profits Rate
19%
Profits ≤ £50,000
Marginal Relief
19–25%
£50K – £250K
Main Rate
25%
Profits > £250,000
Ring-fence profits (oil & gas)
UK Corporation Tax Payable
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Detailed Breakdown

UK Corporation Tax — Key Facts 2026

The UK main Corporation Tax rate is 25% for companies with profits over £250,000. Companies with profits under £50,000 pay the small profits rate of 19%. Profits between £50,000 and £250,000 get marginal relief.

Marginal Relief: Reduces the effective CT rate smoothly between 19% and 25% for companies with profits between £50,000 and £250,000. The relief is calculated as: (Upper Limit − Profits) × (Profits / Augmented Profits) × 3/200.

Associated Companies: The £50,000 and £250,000 limits are divided by the number of associated companies (including the company itself). Two associated companies each get a £25,000 small profits threshold.

Frequently Asked Questions

What is UK Corporation Tax Marginal Relief?+
Marginal Relief reduces the CT bill for companies with profits between £50,000 and £250,000. The formula tapers the tax rate between 19% and 25%, so companies just above £50K pay closer to 19% and those just below £250K pay closer to 25%.
How do R&D tax credits work?+
SME R&D Relief: SMEs can deduct an extra 86% of qualifying R&D costs (merged scheme from April 2024). RDEC: Large companies get a 20% above-the-line credit on qualifying R&D expenditure, reducing CT payable. Both schemes reward UK innovation.
When must UK Corporation Tax be paid?+
For companies with profits under £1.5 million, CT is due 9 months and 1 day after the end of the accounting period. Large companies with profits over £1.5 million pay quarterly instalment payments during the year.
What counts as associated companies for CT?+
A company is associated if it controls or is controlled by another company, or both are under common control. This includes subsidiaries, parent companies, and sister companies. Each associated company reduces the small profits and marginal relief limits.