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🇬🇧 UK onlyCorporation Tax Calculator (UK)
Enter your company's turnover and expenses to see your taxable profit, UK Corporation Tax bill (including marginal relief between £50,000 and £250,000), effective tax rate, and net profit after tax. Rates shown are for FY 2025/26.
Income
Total sales / income for the accounting period, before any expenses.
Bank interest, rental income, or other taxable receipts.
Expenses
Direct costs of producing goods or services sold — stock, materials, direct labour.
Salaries, rent, utilities, marketing, software, professional fees, insurance.
Tax-deductible allowances on equipment, machinery and qualifying assets (e.g. Annual Investment Allowance).
Company structure
Number of other companies under common control. Each one reduces the £50k and £250k thresholds proportionally. Leave at 0 if your company stands alone.
Rates shown are UK Corporation Tax for financial year 2025/26 (1 April 2025 – 31 March 2026). For limited companies only — sole traders pay Income Tax and NI instead.
Tax breakdown
Corporation Tax is due 9 months and 1 day after your accounting period ends; the CT600 return is due 12 months after. This estimate is for guidance only — confirm figures with your accountant.
How UK Corporation Tax works
Since April 2023, UK Corporation Tax is no longer a single flat rate. It uses two rates with a tapered band between them, so the rate your company pays depends on how much profit it makes.
Rates for FY 2025/26
- Small profits rate — 19%: applies if taxable profits are £50,000 or less.
- Main rate — 25%: applies if taxable profits are £250,000 or more.
- Marginal relief: between £50,000 and £250,000, tax is charged at 25% with relief deducted, giving a smooth taper from 19% up to 25%.
The marginal relief formula
When profits fall between the two thresholds, HMRC's formula is:
Marginal relief = (Upper limit − Taxable profits) × (3 ÷ 200)
Corporation Tax = (Taxable profits × 25%) − Marginal relief
The standard fraction of 3/200 produces a marginal rate of 26.5% on every pound between £50,000 and £250,000 — a quirk worth knowing if you're planning bonuses or capital purchases near the threshold.
Worked example
Scenario: a company with £160,000 of taxable profit, no associated companies.
Step 1: £160,000 × 25% = £40,000
Step 2: Marginal relief = (£250,000 − £160,000) × (3 ÷ 200) = £1,350
Step 3: Corporation Tax = £40,000 − £1,350 = £38,650
Effective rate: 24.16% — sitting between the small-profits 19% and the main 25%, as you'd expect.
Associated companies
If your company is part of a group or has associates under common control, the £50,000 and £250,000 thresholds are divided by the total number of associated companies (including itself). With one other associate, the limits halve to £25,000 and £125,000 — so smaller profits hit the marginal band sooner.
Frequently asked questions
How is UK Corporation Tax calculated in 2025/26?
Corporation Tax depends on your taxable profit. Profits up to £50,000 are taxed at the small profits rate of 19%. Profits of £250,000 or more are taxed at the main rate of 25%. Profits between those thresholds are taxed at 25% with marginal relief, which tapers the effective rate between 19% and 25%.
What is marginal relief and how is it calculated?
Marginal relief reduces the Corporation Tax bill for companies with profits between £50,000 and £250,000. The formula is (£250,000 − taxable profits) × (3 ÷ 200). You start by charging 25% on all profits, then subtract the marginal relief amount. The result is a smooth taper from 19% up to 25%.
Do associated companies affect the thresholds?
Yes. If your company has associated companies (broadly, companies under common control), the £50,000 lower limit and £250,000 upper limit are divided by the total number of associated companies, including your own. For example, with one associate the limits become £25,000 and £125,000.
What expenses can I deduct from turnover?
Allowable business expenses include cost of sales, staff wages, rent and utilities, professional fees, marketing, insurance, and qualifying capital allowances on equipment. Drawings, dividends, fines, and client entertaining are generally not deductible. This calculator assumes you've already adjusted for any non-deductible items.
When is Corporation Tax due?
Most companies pay Corporation Tax 9 months and 1 day after the end of their accounting period. The CT600 return is due 12 months after the period end. Large companies (profits over £1.5m, adjusted for associates) pay in quarterly instalments instead.
Is this calculator suitable for sole traders?
No. Sole traders and partnerships pay Income Tax and National Insurance on their profits, not Corporation Tax. This calculator is for UK limited companies only. Sole traders should use the Salary Calculator or check HMRC's self-employment guidance.