UK Corporation Tax Calculator
Calculate your company’s corporation tax liability for the current financial year
How is Corporation Tax Calculated in the UK? (2024 Comprehensive Guide)
Corporation tax is a direct tax levied on the profits of limited companies and other organisations in the UK. Understanding how corporation tax is calculated is essential for business owners, accountants, and financial directors to ensure compliance with HMRC regulations and optimise tax efficiency.
1. Corporation Tax Basics
1.1 What is Corporation Tax?
Corporation tax is a tax on the taxable profits of:
- Limited companies
- Foreign companies with UK branches or offices
- Clubs, co-operatives, and other unincorporated associations (e.g., community groups or sports clubs)
1.2 Who Pays Corporation Tax?
You must pay corporation tax if you run a:
- Limited company
- Any foreign company with a UK branch or office
- Club, co-operative or other unincorporated association (e.g., a community group or sports club)
1.3 What Profits Are Taxable?
Corporation tax is charged on:
- Trading profits (from doing business)
- Investments
- Selling assets for more than they cost (chargeable gains)
2. Corporation Tax Rates (2024/25)
The UK corporation tax rates for the financial year 2024/25 (1 April 2024 to 31 March 2025) are as follows:
| Profit Range | Main Rate (25%) | Small Profits Rate (19%) | Marginal Relief |
|---|---|---|---|
| Up to £50,000 | No | Yes | No |
| £50,001 to £250,000 | Partial | Partial | Yes |
| Over £250,000 | Yes | No | No |
2.1 Main Rate (25%)
Companies with profits over £250,000 pay corporation tax at the main rate of 25%. This rate was increased from 19% in April 2023 to help fund public services.
2.2 Small Profits Rate (19%)
Companies with profits of £50,000 or less continue to pay corporation tax at the small profits rate of 19%. This rate is designed to support small businesses and startups.
2.3 Marginal Relief
For companies with profits between £50,001 and £250,000, marginal relief provides a gradual increase in the effective corporation tax rate. The relief reduces the tax bill, ensuring a smooth transition between the small profits rate and the main rate.
3. How to Calculate Corporation Tax
3.1 Step 1: Determine Your Accounting Period
Your accounting period is typically 12 months, but it can be shorter (e.g., for your first accounting period or if you change your accounting date). The length of your accounting period affects how your profits are annualised for tax purposes.
3.2 Step 2: Calculate Taxable Profits
Taxable profits are calculated by:
- Starting with your company’s net profit (from your annual accounts)
- Adding back any disallowable expenses (e.g., client entertainment, depreciation)
- Subtracting any allowable deductions (e.g., capital allowances, trading losses from previous years)
- Adding chargeable gains (profits from selling assets)
3.3 Step 3: Apply the Correct Tax Rate
Once you have your taxable profits, apply the appropriate tax rate based on your profit level:
- Up to £50,000: 19% (small profits rate)
- £50,001 to £250,000: Marginal relief applies (effective rate between 19% and 25%)
- Over £250,000: 25% (main rate)
3.4 Step 4: Calculate Marginal Relief (If Applicable)
Marginal relief reduces your corporation tax bill if your profits fall between £50,001 and £250,000. The formula for marginal relief is:
Marginal Relief = (Upper Limit – Taxable Profits) × (Main Rate – Small Profits Rate) / Upper Limit
Where:
- Upper Limit: £250,000 (reduced if you have associated companies)
- Main Rate: 25%
- Small Profits Rate: 19%
3.5 Step 5: Adjust for Associated Companies
If your company has associated companies (companies under common control), the £50,000 and £250,000 thresholds are divided by the number of associated companies. For example:
- With 1 associated company: Thresholds become £25,000 and £125,000
- With 2 associated companies: Thresholds become £16,667 and £83,333
4. Example Calculations
4.1 Example 1: Profits Below £50,000
Scenario: Your company has taxable profits of £40,000 and no associated companies.
Calculation: £40,000 × 19% = £7,600
Corporation Tax Due: £7,600
4.2 Example 2: Profits Between £50,001 and £250,000 (With Marginal Relief)
Scenario: Your company has taxable profits of £100,000 and no associated companies.
Step 1: Calculate tax at the main rate: £100,000 × 25% = £25,000
Step 2: Calculate marginal relief:
(£250,000 – £100,000) × (25% – 19%) / £250,000 = £3,600
Step 3: Subtract marginal relief: £25,000 – £3,600 = £21,400
Corporation Tax Due: £21,400 (effective rate: 21.4%)
4.3 Example 3: Profits Over £250,000
Scenario: Your company has taxable profits of £300,000 and no associated companies.
Calculation: £300,000 × 25% = £75,000
Corporation Tax Due: £75,000
5. Corporation Tax Payment Deadlines
Your corporation tax payment is due 9 months and 1 day after the end of your accounting period. For example:
- If your accounting period ends on 31 March 2025, your payment is due by 1 January 2026.
- If your accounting period ends on 30 September 2024, your payment is due by 1 July 2025.
Your Company Tax Return (form CT600) must be filed with HMRC 12 months after the end of your accounting period.
6. Allowances and Reliefs
6.1 Capital Allowances
Capital allowances let you deduct the cost of certain capital assets (e.g., equipment, machinery) from your taxable profits. Common types include:
- Annual Investment Allowance (AIA): Up to £1 million per year (as of 2024)
- First-Year Allowances: 100% deduction for qualifying energy-efficient or low-emission vehicles
- Writing Down Allowances: For assets not covered by AIA (e.g., 18% for general plant and machinery)
6.2 Research and Development (R&D) Relief
If your company invests in innovation, you may qualify for R&D relief, which can:
- Reduce your taxable profits (by up to 230% of qualifying costs for SMEs)
- Provide a cash credit if you’re loss-making
6.3 Trading Losses
If your company makes a loss, you can:
- Carry it back to offset against profits from the previous year
- Carry it forward to offset against future profits
- Surrender it for a tax refund (under certain conditions)
7. Common Mistakes to Avoid
- Missing the Deadline: Late payments incur interest and penalties. Set reminders for the 9-month-and-1-day deadline.
- Incorrect Profit Calculation: Ensure you add back disallowable expenses (e.g., entertainment, depreciation) and claim all allowable deductions.
- Ignoring Associated Companies: Forgetting to divide the £50,000 and £250,000 thresholds by the number of associated companies can lead to underpayment.
- Not Claiming Reliefs: Many companies miss out on capital allowances, R&D relief, or marginal relief due to lack of awareness.
- Incorrect Accounting Period: Using the wrong period (e.g., calendar year instead of financial year) can distort your tax calculation.
8. Corporation Tax vs. Other Business Taxes
| Tax Type | Who Pays? | Rate (2024/25) | Key Differences |
|---|---|---|---|
| Corporation Tax | Limited companies, foreign companies with UK branches | 19% or 25% (with marginal relief) | Paid on company profits; filed annually via CT600 |
| Income Tax | Sole traders, partners, employees | 20%–45% (depending on income) | Paid on personal income; filed via Self Assessment |
| VAT | Businesses with turnover > £90,000 (2024 threshold) | 20% (standard rate) | Charged on sales; quarterly returns |
| National Insurance | Employers, employees, self-employed | Varies (e.g., 12%–13.8% for employers) | Paid on salaries/wages; separate from corporation tax |
9. How to Reduce Your Corporation Tax Bill Legally
- Claim All Allowable Expenses: Ensure you deduct all legitimate business expenses (e.g., salaries, rent, utilities, travel).
- Maximise Capital Allowances: Use the Annual Investment Allowance (AIA) to deduct the full cost of qualifying assets up to £1 million.
- Utilise R&D Relief: If your company innovates, claim R&D tax credits to reduce your taxable profits or receive cash back.
- Pension Contributions: Employer pension contributions are tax-deductible and can lower your taxable profits.
- Loss Relief: Carry forward or back trading losses to offset against profits in other years.
- Dividend Planning: Paying dividends (taxed at lower rates than salary) can be tax-efficient for director-shareholders.
- Structuring Associated Companies: If you control multiple companies, structuring them carefully can optimise threshold limits.
10. Recent Changes to Corporation Tax (2023–2024)
10.1 Increase in Main Rate (April 2023)
From 1 April 2023, the main corporation tax rate increased from 19% to 25% for companies with profits over £250,000. This was the first increase since 2011.
10.2 Introduction of Marginal Relief
The 2023 reforms introduced marginal relief for profits between £50,001 and £250,000, replacing the previous flat 19% rate for all profits.
10.3 Changes to Capital Allowances
The Annual Investment Allowance (AIA) was permanently set at £1 million in 2023, providing long-term certainty for businesses investing in plant and machinery.
10.4 Digitalisation of Tax Reporting
HMRC is rolling out Making Tax Digital (MTD) for Corporation Tax, requiring companies to keep digital records and submit quarterly updates. This is expected to be mandatory from April 2026.
11. Corporation Tax for Small Businesses
11.1 Small Profits Rate (19%)
Companies with profits of £50,000 or less continue to pay corporation tax at 19%, providing relief for startups and small businesses.
11.2 Cash Basis Accounting
Small unincorporated businesses (e.g., sole traders) can use cash basis accounting, simplifying tax calculations by recognising income and expenses when money changes hands.
11.3 Simplified Expenses
Small businesses can use flat rates for certain expenses (e.g., business mileage at 45p per mile for the first 10,000 miles), reducing record-keeping burdens.
12. Corporation Tax for Large Companies
12.1 Main Rate (25%)
Large companies (profits over £250,000) pay the main rate of 25%. This aligns the UK with the OECD average corporation tax rate.
12.2 Quarterly Instalment Payments
Companies with profits over £1.5 million (or £375,000 for close investment-holding companies) must pay corporation tax in quarterly instalments, starting 6 months and 13 days after the accounting period begins.
12.3 Transfer Pricing Rules
Large multinational companies must comply with transfer pricing rules, ensuring transactions between connected entities are priced at arm’s length to prevent tax avoidance.
13. Corporation Tax and Dividends
When a company pays dividends to shareholders, the process involves:
- Company Level: Dividends are paid from post-tax profits (no corporation tax deduction).
- Shareholder Level: Shareholders pay dividend tax (8.75%–39.35% in 2024/25, depending on their income tax band).
Example: If your company has £100,000 in profits:
- Corporation tax at 19%–25% is paid first (e.g., £19,000–£25,000).
- The remaining £75,000–£81,000 can be distributed as dividends.
- Shareholders then pay dividend tax on the amount received.
14. Corporation Tax and Salaries
Paying salaries is tax-deductible for corporation tax purposes, reducing your company’s taxable profits. However, salaries are subject to:
- Income Tax: Deductible via PAYE (20%–45%)
- National Insurance: Employer (13.8%) and employee (12%) contributions
Tax-Efficient Strategy: Many director-shareholders pay a small salary (up to the National Insurance threshold) and top up with dividends to minimise overall tax liability.
15. Corporation Tax for Foreign Companies
Foreign companies with a UK branch or permanent establishment must pay UK corporation tax on:
- Trading profits attributable to the UK branch
- Income from UK property
- Chargeable gains on UK assets
Double Taxation Relief: The UK has double taxation treaties with over 130 countries, allowing foreign companies to claim relief for tax paid in the UK against their home country tax bill.
16. Corporation Tax and Losses
16.1 Trading Losses
If your company makes a trading loss, you can:
- Carry Back: Offset against profits from the previous 12 months (unlimited for losses up to £2 million).
- Carry Forward: Offset against future profits indefinitely.
- Surrender: For a tax refund (under certain conditions, e.g., R&D losses).
16.2 Capital Losses
Capital losses (from selling assets) can only be offset against capital gains in the same or future accounting periods.
17. Corporation Tax and Group Companies
If your company is part of a group, special rules apply:
- Group Relief: Losses can be surrendered between group companies to offset against profits.
- Transfer of Assets: Assets can be transferred between group companies without triggering chargeable gains.
- Associated Companies: The £50,000 and £250,000 thresholds are divided by the number of associated companies.
18. Corporation Tax and Property Income
Rental income from property is taxable under corporation tax rules. Allowable expenses include:
- Mortgage interest (restricted to 20% tax credit for residential properties)
- Repairs and maintenance
- Agent fees and ground rents
- Insurance and council tax (if paid by the landlord)
19. Corporation Tax and Intellectual Property
The Patent Box regime allows companies to apply a lower 10% corporation tax rate to profits earned from patented inventions. To qualify:
- Your company must own or exclusively license the patent.
- The patent must be granted by the UK Intellectual Property Office or European Patent Office.
- Your company must have undertaken qualifying development on the patented invention.
20. Corporation Tax and Brexit
Since Brexit, UK corporation tax rules for EU trade have changed:
- No VAT on EU Imports: VAT is now charged at the point of import (postponed accounting).
- Customs Duties: May apply to goods imported from the EU, depending on the trade agreement.
- State Aid Rules: The UK is no longer bound by EU state aid rules, allowing more flexibility in tax incentives.
21. Corporation Tax and ESG (Environmental, Social, Governance)
Companies investing in ESG initiatives may benefit from:
- Enhanced Capital Allowances: 100% first-year allowance for energy-efficient equipment.
- R&D Relief: For developing green technologies.
- Tax Incentives: For electric vehicle charging points, renewable energy installations, etc.
22. Corporation Tax and Digital Businesses
The UK introduced a Digital Services Tax (DST) in 2020, charging 2% on revenues of large digital businesses (e.g., social media platforms, search engines) with global revenues over £500 million and UK revenues over £25 million. This is separate from corporation tax but may affect overall tax strategy.
23. Corporation Tax and Insolvency
If your company becomes insolvent:
- HMRC is a preferential creditor for certain taxes (including VAT and PAYE), but not for corporation tax.
- Unpaid corporation tax ranks as an unsecured debt in insolvency proceedings.
- Directors may be personally liable if tax avoidance or evasion is proven.
24. Corporation Tax and Mergers & Acquisitions
During mergers or acquisitions, consider:
- Tax Losses: Can they be carried forward in the new structure?
- Stamp Duty: Payable on share transfers (0.5% for UK shares).
- Due Diligence: Review the target company’s tax position (e.g., unpaid liabilities, pending HMRC investigations).
25. Corporation Tax and Pensions
Employer pension contributions are tax-deductible for corporation tax purposes, reducing your taxable profits. Key points:
- Contributions must be “wholly and exclusively” for business purposes.
- There is no upper limit, but excessive contributions may be challenged by HMRC.
- Contributions for directors must be “reasonable” for their role.
26. Corporation Tax and Charitable Donations
Donations to registered charities are tax-deductible. You can:
- Deduct the donation from taxable profits (reducing corporation tax).
- Claim Gift Aid (if the charity is eligible), allowing the charity to reclaim basic-rate tax.
27. Corporation Tax and HMRC Enquiries
HMRC may open an enquiry into your Company Tax Return if:
- There are inconsistencies or errors in your return.
- Your profits or tax liability seem unusually low.
- You’re selected for a random compliance check.
Penalties for Errors:
- Careless Mistakes: Up to 30% of the additional tax due.
- Deliberate Errors: Up to 70% of the additional tax due.
- Deliberate Concealment: Up to 100% of the additional tax due.
28. Corporation Tax and International Tax Planning
Multinational companies must navigate:
- Controlled Foreign Company (CFC) Rules: Prevent profit-shifting to low-tax jurisdictions.
- Diverted Profits Tax (DPT): 25% tax on profits artificially diverted from the UK.
- Double Taxation Treaties: Over 130 treaties to avoid double taxation on cross-border income.
29. Corporation Tax and the OECD Global Minimum Tax
The UK implemented the OECD’s 15% global minimum tax (Pillar Two) in 2023, affecting multinational enterprises (MNEs) with global revenues over €750 million. Key features:
- Top-Up Tax: If a company’s effective tax rate in a jurisdiction is below 15%, a top-up tax applies.
- Domestic Implementation: The UK’s Multinational Top-Up Tax and Domestic Top-Up Tax ensure compliance.
30. Corporation Tax and the Future
Upcoming changes to watch:
- Making Tax Digital (MTD) for Corporation Tax: Mandatory digital record-keeping and quarterly reporting from April 2026.
- Increased Scrutiny on Tax Avoidance: HMRC is investing in AI and data analytics to detect non-compliance.
- Potential Rate Changes: Future governments may adjust rates based on economic conditions.
31. Frequently Asked Questions (FAQs)
31.1 Do Sole Traders Pay Corporation Tax?
No. Sole traders pay Income Tax on their business profits via Self Assessment, not corporation tax.
31.2 Can I Pay Corporation Tax Early?
Yes. You can pay corporation tax at any time before the deadline. Early payment may help with cash flow planning.
31.3 What Happens If I Pay Corporation Tax Late?
HMRC charges interest on late payments (currently 7.75% as of 2024). Penalties may also apply for late filing of your Company Tax Return.
31.4 Can I Offset Personal Expenses Against Corporation Tax?
No. Only business-related expenses can be deducted. Personal expenses (e.g., personal travel, non-business entertainment) are not allowable.
31.5 How Do I Claim R&D Tax Relief?
You claim R&D relief through your Company Tax Return (CT600) by completing the relevant sections and providing details of qualifying expenditures. Many companies use specialist advisors to maximise their claim.
31.6 What Is the Difference Between Corporation Tax and VAT?
| Feature | Corporation Tax | VAT |
|---|---|---|
| Who Pays? | Limited companies | Businesses with turnover > £90,000 (2024 threshold) |
| What’s Taxed? | Company profits | Sales of goods/services |
| Rate | 19% or 25% | 20% (standard rate) |
| Filing Frequency | Annually | Quarterly |
| Payment Deadline | 9 months and 1 day after accounting period | 1 month and 7 days after VAT period |
31.7 Can I Reduce Corporation Tax by Paying a Bonus?
Yes. Salaries and bonuses are tax-deductible, reducing your company’s taxable profits. However, the bonus is subject to Income Tax and National Insurance for the employee.
31.8 What Is the Corporation Tax Rate for Banks?
Banks and building societies pay an additional 8% surcharge on top of the main rate, resulting in a total rate of 33% for profits over £250,000.
31.9 Do I Need to Pay Corporation Tax If I Make a Loss?
No. If your company makes a loss, you won’t pay corporation tax for that period. However, you must still file a Company Tax Return.
31.10 How Do I Amend a Corporation Tax Return?
You can amend your Company Tax Return (CT600) within 12 months of the original filing deadline. Use HMRC’s online services or commercial software to submit the amendment.