Marginal relief prevents the corporation tax rate from jumping sharply from 19% to 25% as profit crosses £50,000. Companies with profits between £50,000 and £250,000 instead pay an effective rate that rises gradually from 19% to 25%. If your profits sit in this range, understanding the formula matters. The marginal rate within the band is approximately 26.5%, higher than either boundary rate.
Updated 2026/27 · LimitedCompanyTaxCalculator.co.uk · Editorial standards · Methodology
For corporation tax in 2026/27, company taxable profits fall into three regions. Profits up to £50,000: 19% applies to all of it. Profits above £250,000: 25% applies to all of it. Profits between £50,000 and £250,000: marginal relief applies, producing an effective rate between 19% and 25%.
The point that surprises most people is that marginal relief does not mean paying 19% on the first £50,000 and 25% on the rest. It is a single effective rate applied to total profit. The formula produces a smooth transition rather than a step.
These thresholds apply to 12-month accounting periods. For shorter or longer periods they are apportioned accordingly.
The corporation tax calculation in the marginal relief band is: Corporation tax = (Profits × 25%) − (Marginal Relief Fraction × (£250,000 − Profits)).
The Marginal Relief Fraction is 3/200. At £100,000 taxable profit: £100,000 × 25% = £25,000. Then 3/200 × (£250,000 − £100,000) = 3/200 × £150,000 = £2,250. Corporation tax = £25,000 − £2,250 = £22,750. Effective rate: 22.75%.
At £175,000 profit: £175,000 × 25% = £43,750. Then 3/200 × £75,000 = £1,125. Corporation tax = £43,750 − £1,125 = £42,625. Effective rate: 24.4%.
Within the marginal relief band, the marginal rate, the rate applied to the last pound of profit, is approximately 26.5%. This is higher than the 25% main rate that applies above £250,000.
This creates a planning opportunity: reducing profit within the band (by making a director pension contribution, for example) saves approximately 26.5p in corporation tax per pound reduced. The same pension contribution above the £250,000 threshold would save 25p, and below the £50,000 threshold it would save 19p.
Directors with profits regularly in the £50,000–£250,000 band should model the effect of pension contributions and other deductions carefully. The potential corporation tax saving per pound is higher in this range than at either boundary.
This calculator uses the standard £50,000 and £250,000 thresholds for a single standalone company. Where a company is associated with one or more others under common control, including by close family relationships, the thresholds are divided equally between them.
Two associated companies means effective thresholds of £25,000 and £125,000. Three associated companies reduces them to approximately £16,667 and £83,333. This can dramatically change the effective corporation tax rate.
HMRC's guidance on associated companies is specific. If you control or are closely connected with other companies, check with an accountant whether the association rules apply before relying on the thresholds shown here.
The corporation tax figure shown in this calculator applies the marginal relief formula automatically where profit falls between £50,000 and £250,000. You can see the effective rate by observing how the corporation tax changes as you adjust company profit.
To explore the impact of director pension contributions within the marginal relief band, enter a pension figure and observe how the corporation tax charge falls. The rate of reduction per pound contributed will be approximately 26.5% in this range, faster than at either boundary.
If you have associated companies, adjust the profit figure to reflect your share of the relevant thresholds, or discuss the position with an accountant who can apply the correct associated company rules to your specific structure.
Approximately 22.75% for a standalone company. Using the marginal relief formula: (£100,000 × 25%) − (3/200 × £150,000) = £25,000 − £2,250 = £22,750.
No. Marginal relief is a single effective rate applied to all profits in the band. The formula produces a rate between 19% and 25% depending on profit level, not a stepped tax at two rates.
Approximately 26.5%, the rate applied to the last pound of profit within the £50,000–£250,000 band. This is higher than either boundary rate and is why pension contributions are particularly efficient for companies in this range.
Associated companies divide the thresholds equally. Two associated companies share thresholds of £25,000 and £125,000. This can significantly raise the effective corporation tax rate compared to a single standalone company.
The limited company tax calculator turns this guidance into a concrete estimate for corporation tax, dividends and personal take-home, based on 2026/27 HMRC rates.