🏢 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

Trading profit (before adjustments) Net profit per accounts — before CT adjustments

Non-trading income (chargeable) Rental income, interest received, etc.

Capital gains (chargeable) Gains on disposal of chargeable assets

Franked investment income (FII) Dividends from non-group UK companies — affects augmented profits only

Deductions & Reliefs

Qualifying deductions (£) Disallowable expenses already added back via CT600 adjustments

Losses brought forward (£) Unutilised trading losses from prior years

R&D enhanced deduction (£) SME or large company R&D relief — enter the additional deduction amount

Other reliefs / allowances (£) Capital allowances add-back, patent box, etc.

Company & Period Details

Accounting period length (months) Enter actual length — thresholds are pro-rated if <12

Number of associated companies Total inc. this company — divides £50k/£250k limits

Tax year (financial year)

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

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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.

Taxable profits (£)

FII (augmented profits adjustment)

Associated companies (total inc. this)

Accounting period (months)

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.

📊 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

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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)

Company profit before director salary (£)

Associated companies (total)

Director Extraction

Director salary per year (£) Deductible from CT profits (salary + Employer NI)

Dividends paid from retained profit (£) Not deductible for CT — paid from post-CT profit

Employer NI on salary (£) Also CT deductible — 13.8% on salary above £9,100

Auto-calculate Employer NI?

💡 Extraction Analysis

CT impact of salary vs dividends

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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.