🏢 Corporation Tax · 2025/26
Corporation Tax Calculator
Calculate UK Corporation Tax for limited companies: small profits rate (19%), main rate (25%), marginal relief (3/200 fraction), associated companies, short accounting periods, and profit extraction planning. Official references: Marginal Relief – GOV.UK → | CT Rates & Allowances →
💰 Profit & Income Details
Trading Profit / Loss
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Deductions & Reliefs
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Company & Period Details
Rate band (live)
Small Profits
19%
Up to £50,000*
Marginal Relief
19–25%
£50k – £250k*
Main Rate
25%
Over £250,000*
* Limits are pro-rated for period <12 months and divided by number of associated companies.
Taxable profits: £0
Adjusted limits shown above
£0
£50,000
£250,000
⚠️ Disclaimer
This is an estimate. Actual CT liability requires a full CT600 return including all adjustments, capital allowances, group relief, and HMRC self-assessment.
CT600 filing – GOV.UK →
🏢 Corporation Tax Result
2025/26 · 12-month period
Enter profit figures and click Calculate Corporation Tax.
📐 Marginal Relief Deep Dive
Profit Scenarios
Compare CT liability across a profit range, or check a single profit figure in detail.
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Marginal Relief Formula (3/200 fraction)
CT = (Profits × 25%) – [3/200 × (Upper Limit – Augmented Profits) × (TTP ÷ Augmented Profits)]
The effective marginal rate within the band is 26.5% — meaning each extra £1 of profit between £50k and £250k incurs 26.5p of tax (25p CT + 1.5p lost marginal relief). Above £250k, each extra £1 costs only 25p. This creates a tax “notch” — in practice, profits between £50k and £250k face a higher marginal rate than those above £250k.
The effective marginal rate within the band is 26.5% — meaning each extra £1 of profit between £50k and £250k incurs 26.5p of tax (25p CT + 1.5p lost marginal relief). Above £250k, each extra £1 costs only 25p. This creates a tax “notch” — in practice, profits between £50k and £250k face a higher marginal rate than those above £250k.
📊 CT at Selected Profit Levels (single company, 12 months)
| Taxable Profits | Tax at 25% | Marginal Relief | CT Liability | Effective Rate |
|---|---|---|---|---|
| £20,000 | — | — | £3,800 | 19.0% |
| £50,000 | — | — | £9,500 | 19.0% |
| £75,000 | £18,750 | –£2,625 | £16,125 | 21.5% |
| £100,000 | £25,000 | –£2,250 | £22,750 | 22.75% |
| £150,000 | £37,500 | –£1,500 | £36,000 | 24.0% |
| £200,000 | £50,000 | –£750 | £49,250 | 24.63% |
| £250,000 | £62,500 | –£0 | £62,500 | 25.0% |
| £500,000 | — | — | £125,000 | 25.0% |
📐 Marginal Relief Result
Step-by-step calculation
Enter profits and click Calculate.
💡 Profit Extraction Planning — salary vs dividends
What this tool does
Models CT impact of paying salary vs dividends to the director/shareholder, including employer NI saving vs CT deductibility and the marginal relief effect.
Company Profit (before salary)
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Director Extraction
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💡 Extraction Analysis
CT impact of salary vs dividends
Enter profit and extraction details and click Run Analysis.
📋 Corporation Tax Rates — History & Reference
Rates from 1 April 2023 (current structure)
| Band | Annual Profits | Rate | Notes |
|---|---|---|---|
| Small Profits | Up to £50,000 | 19% | Single company, full 12-month period |
| Marginal Band | £50,001 – £250,000 | 19–25% | Marginal relief applies; effective marginal rate = 26.5% |
| Main Rate | Over £250,000 | 25% | No marginal relief |
Historical CT rates (for reference)
| Period | Rate (all profits) | Notes |
|---|---|---|
| 1 Apr 2017 – 31 Mar 2023 | 19% | Single flat rate |
| 1 Apr 2015 – 31 Mar 2017 | 20% | Single flat rate |
| 1 Apr 2023 onwards | 19% / 25% | Tiered with marginal relief |
Associated companies — threshold division
| Total associated companies | Lower limit | Upper limit |
|---|---|---|
| 1 (just this company) | £50,000 | £250,000 |
| 2 | £25,000 | £125,000 |
| 3 | £16,667 | £83,333 |
| 4 | £12,500 | £62,500 |
| 5 | £10,000 | £50,000 |
Short accounting periods (pro-rata)
| Period | Lower limit (÷ by assoc.) | Upper limit (÷ by assoc.) |
|---|---|---|
| 12 months | £50,000 | £250,000 |
| 9 months | £37,500 | £187,500 |
| 6 months | £25,000 | £125,000 |
| 3 months | £12,500 | £62,500 |
CT payment & filing deadlines
| Company size | Payment due | CT600 filing |
|---|---|---|
| Small / medium (profits ≤ £1.5m) | 9 months + 1 day after AP end | 12 months after AP end |
| Large (profits > £1.5m) | Quarterly instalments | 12 months after AP end |
| Very large (profits > £20m) | Earlier quarterly (month 3, 6, 9, 12) | 12 months after AP end |
26.5% effective marginal rate — key planning point
In the marginal band (£50k–£250k), each additional £1 of profit costs 26.5p in effective CT (25p + 1.5p lost relief). This is higher than the 25p rate above £250k. Consider pension contributions, salary structuring, R&D claims, and capital allowances to manage profit levels within this band.
Associated companies — key test
Companies are associated if one has control of the other, or both are under common control. This includes companies owned by family members or connected parties in many cases. From 1 April 2023, the rules were updated — a company is an associated company for the entire tax year even if it only became associated part-way through.