What are the UK corporation tax rates from April 2023?

From 1 April 2023, the small profits rate is 19% on profits up to £50,000 and the main rate is 25% on profits over £250,000. Profits between £50,001 and £250,000 attract marginal relief, which tapers the effective rate between 19% and 25%.

How does marginal relief work?

Marginal relief reduces the corporation tax charge for companies with profits between £50,001 and £250,000. The relief is calculated as: (Upper Limit − Profits) × (Profits / Augmented Profits) × 3/200. This produces an effective rate that rises smoothly from 19% to 25% across the band.

What are associated companies and why do they matter?

Associated companies share control with your company (e.g. companies under common ownership). HMRC divides the £50,000 and £250,000 profit thresholds equally among all associated companies plus your own. For example, with one associated company, thresholds become £25,000 and £125,000.

Does this calculator cover the full accounting period?

The calculator assumes a standard 12-month accounting period. For short or long periods, HMRC pro-rates the thresholds. Adjust your input to reflect annualised profits if your period differs.

Are there any surcharges or reliefs not included?

This tool covers the core corporation tax liability and marginal relief only. It does not include the Bank Surcharge, the Diverted Profits Tax, R&D credits, capital allowances, or group relief. Consult a tax adviser for a complete picture.

What is augmented profits for marginal relief purposes?

Augmented profits equal taxable profits plus exempt distributions received from non-group companies. For most small companies these figures are identical. This calculator assumes augmented profits equal taxable profits.

UK Corporate Tax Calculator

Name: UK Corporate Tax Calculator
Availability: InStock
Author: Nham Vu

Enter your company's taxable profits to instantly calculate UK corporation tax with small profits rate, main rate, and marginal relief for 2023/24 onwards.

Tax Inputs

Taxable Profits

Your company's profits chargeable to corporation tax for the accounting period.

Associated Companies (optional)

Number of companies associated with yours under HMRC rules. Thresholds are divided equally among all companies.

2023/24 rates: 19% (profits up to £50k), 25% main rate (profits above £250k), marginal relief taper in between. Thresholds divided by number of associated companies + 1.

Enter taxable profits to see your UK corporation tax breakdown.

Corporation Tax Liability

£0

—

Effective Rate

0.00%

Marginal Relief

£0

After-Tax Profit

£0

Thresholds in use: small profits limit £50,000 / upper limit £250,000

Item	Amount	% of Profits
Taxable Profits	—	100.00%
Gross Tax at Main Rate (25%)	—	—
Marginal Relief	—	—
Tax Liability	—	—
After-Tax Profit	—	—

Effective Tax Rate 0.00%

0% 19% small profits 25% main

Done!

Summary

Enter your company's taxable profits to instantly calculate UK corporation tax with small profits rate, main rate, and marginal relief for 2023/24 onwards.

How it works

Enter your company's taxable profits for the accounting period.
If you have associated companies, enter the count to adjust the profit thresholds.
Click Calculate to see your corporation tax liability.
Review the rate band applied — small profits (19%), marginal relief, or main rate (25%).
Check the marginal relief amount and effective tax rate in the breakdown.
Click Reset to clear all fields and start over.

Use cases

Estimating quarterly corporation tax payments for HMRC.
Modelling after-tax profit in a business plan or investor pitch.
Understanding the marginal relief taper between £50,000 and £250,000.
Comparing tax liability across different profit scenarios.
Assessing the impact of associated companies on profit thresholds.
Quick sanity-check before filing a Company Tax Return (CT600).

Frequently Asked Questions

Last updated: 2026-06-25 · Reviewed by Nham Vu