Corporation Tax UK: Rates, Deadlines & How to File

Tax Guides · 10 min read · Updated 2026-03-20

A comprehensive guide to UK corporation tax, covering the 25% main rate, small profits rate, marginal relief, CT600 filing, and payment deadlines.

Written by Krishna, Founder & HMRC-registered tax agent at TaxRoot.

What is the small profits rate of corporation tax?

The small profits rate is 19% and applies to companies with taxable profits of £50,000 or less. If your company has associated companies, this threshold is divided equally among them. For example, if you have one associated company, the small profits threshold drops to £25,000 for each company. This lower…

Related TaxRoot services

• Self Assessment tax return — £134 flat fee
• Corporation Tax + annual accounts — from £389/yr
• Making Tax Digital for Income Tax — £34/month
• VAT returns — from £39/month
• UK Limited Company Registration — £100

Corporate Tax Services · See full TaxRoot pricing · More TaxRoot guides