The marginal Corporation Tax rates

The rate of Corporation Tax payable depends on the level of a company’s taxable profits. The main rate is 25% and applies where profits exceed £250,000. At the other end of the scale, companies with profits of £50,000 or less benefit from the Small Profits Rate, which remains at 19%.

For businesses with profits between these thresholds, marginal relief applies. Rather than facing a sharp increase in tax, companies experience a gradual rise in the effective rate as profits move from £50,000 towards £250,000. This ensures a smoother transition between the lower and higher rates.

It is important to note that the £50,000 and £250,000 thresholds are not always fixed. They are reduced where a company has associated companies or where the accounting period is shorter than 12 months, which can bring more businesses into the marginal relief band.

In practice, Corporation Tax is initially calculated at the main rate of 25%, with marginal relief then deducted to arrive at the final liability. The relief is calculated using a standard fraction of 3/200.

The marginal rates help smaller companies to pay less Corporation Tax based on their profit level and circumstances. 

Source:HM Revenue & Customs | 30-03-2026
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Aitch
Aitch is the visionary founder and CEO of CIGMA Accounting Ltd, a boutique accounting and tax advisory firm with offices in Wimbledon and Farringdon, London. With over a decade of experience, Aitch has built a reputation for strategic tax planning, complex HMRC compliance resolution, and innovative AI-powered accounting workflows that help SMEs, landlords, and high-net-worth clients streamline their finances. His expertise spans corporation tax, inheritance tax planning, R&D tax credit claims, capital allowances, and international tax matters, making him a trusted advisor for clients seeking to minimise tax liabilities while staying fully compliant. Aitch is passionate about bridging traditional accounting principles with cutting-edge digital solutions, allowing businesses to operate efficiently and future-proof their financial systems. Through CIGMA, he aims to make accounting smarter, faster, and more human-centric - empowering clients to focus on growth while staying ahead of regulatory changes.