How Is UK Corporation Tax Calculated in 2026?
A company with augmented profits at or below the adjusted lower limit
will normally pay Corporation Tax at the 19% small profits rate.
The 25% main rate normally applies when augmented profits exceed the
adjusted upper limit. Marginal Relief may reduce the tax bill when
augmented profits fall between the two limits.
Marginal Relief = (Upper limit − augmented profits) ×
(taxable profits ÷ augmented profits) × 3 ÷ 200
What Are Augmented Profits?
Augmented profits generally include taxable total profits plus certain
exempt distributions received by the company.
Augmented profits help determine which Corporation Tax rate applies.
The tax itself is calculated on taxable total profits rather than on
the exempt distributions.
Augmented profits = taxable total profits + relevant exempt distributions
How Do Associated Companies Affect the Limits?
The standard £50,000 and £250,000 limits are divided by the total number
of associated companies, including the company being calculated.
For example, where a company has one associated company, the standard
limits are normally divided by two.
- No associated companies: £50,000 and £250,000 limits
- One associated company: £25,000 and £125,000 limits
- Three associated companies: £12,500 and £62,500 limits
What Is Not Included in This Estimate?
The calculator provides a simplified estimate for an ordinary UK
company. It does not calculate every relief, allowance, surcharge or
specialist Corporation Tax rule.
- Capital allowances and Annual Investment Allowance claims
- Trading losses carried forward or carried back
- Research and development tax relief
- Patent Box relief
- Banking company surcharges
- Ring Fence Corporation Tax
- Quarterly instalment payment rules for large companies