Company details
£
Corporation tax due
£0
for this accounting period
19%Rate applied
£0Marginal relief
£0Taxable profit
£0Post-tax profit
For guidance only — not financial, tax or legal advice. Verify with a qualified professional.
About corporation tax 2026/27
What are the corporation tax rates for 2026/27?
There are two rates: the small profits rate of 19% applies to companies with taxable profits up to £50,000. The main rate of 25% applies to profits above £250,000. Companies with profits between £50,000 and £250,000 pay the main rate of 25% but with marginal relief — effectively creating a gradual increase. The effective marginal rate in this band is approximately 26.5%.
What is marginal relief and how does it work?
Marginal relief reduces the amount of corporation tax paid by companies in the £50,000–£250,000 profit band. The formula is: Relief = (Upper Limit − Profits) × (Profits / Augmented Profits) × 3/200. This creates an effective marginal rate of approximately 26.5% within the band, rather than jumping straight to 25% on all profits. Companies with associated companies have the thresholds divided by the number of associated companies.
What counts as an associated company?
A company is associated with another if one controls the other, or both are under common control. This includes companies controlled by the same person or group. If you have 2 associated companies, the lower threshold becomes £25,000 and the upper threshold £125,000. This is a significant consideration for directors who run multiple companies.
When do I pay corporation tax?
For companies with annual taxable profits under £1.5 million, corporation tax is due 9 months and 1 day after the end of the accounting period. So for a company with a 31 March year end, CT is due on 1 January. Large companies (profits over £1.5m) pay quarterly instalment payments during the year. File your CT600 return within 12 months of the accounting period end.