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Tax · Apr 2026

Corporation tax marginal relief explained

Corporation tax isn't always a single headline rate. Understanding marginal relief is essential for effective planning and cashflow.

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Introduction

Corporation tax in the UK is not always as simple as a single headline rate. For many businesses, marginal relief plays an important role in determining the actual tax payable. Understanding how it works is essential for effective tax planning and cashflow management.

What is marginal relief?

Marginal relief is a mechanism that smooths the transition between corporation tax bands. Instead of a sudden jump from a lower to higher tax rate, relief is gradually reduced as profits increase. This ensures a more balanced tax curve for companies with profits within certain thresholds.

How it works in practice

Companies with profits between the lower and upper thresholds do not pay a single flat rate. Instead:

  • Lower profits benefit from reduced effective rates
  • Higher profits gradually lose access to relief
  • The effective tax rate increases progressively

Why it matters for businesses

Marginal relief can significantly impact:

  • Effective tax rate
  • Cashflow forecasting
  • Dividend planning
  • Investment decisions

Many businesses underestimate its impact when planning profits.

Common planning considerations

Businesses should consider:

  • Timing of income and expenses
  • Bonus payments and salary structures
  • Capital expenditure planning
  • Group structure optimisation

How LMJ Group supports clients

We help businesses:

  • Understand effective tax rates
  • Model corporation tax liabilities
  • Plan profit extraction efficiently
  • Integrate tax planning into wider financial strategy

Conclusion

Marginal relief is a key part of corporation tax planning for growing businesses. Understanding how it applies can help improve tax efficiency and avoid unexpected liabilities.

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