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How to Calculate Company Tax in 2025
Every limited company in the UK must pay Corporation Tax on its profits. But if you run a small company, you may be entitled to lower tax rates and marginal relief. This guide shows you how to calculate your company tax in 2025 and shares smart tax planning tips to reduce your bill.
Why this matters for small businesses
Small companies often have tight margins. So, understanding your Corporation Tax position means you can manage cash flow better, avoid mistakes, and make informed financial decisions. Many small company owners also handle accounts themselves—so clear guidance can save you time and stress.
Corporation Tax rates in 2025
As of April 2025, the UK uses a tiered system for Corporation Tax:
Small profits rate: 19% on profits up to £50,000
Main rate: 25% on profits over £250,000
Marginal relief: a gradual increase between those limits
Note: If your company controls other active businesses (associated companies), you must divide the limits equally. So, two companies mean the small profits rate applies up to £25,000 only.
Step-by-step: Calculate your company tax
Here’s how small companies can work out Corporation Tax in 5 simple steps.
Step 1: Start with your net profit
Take the profit figure before tax from your final accounts.
Step 2: Adjust for tax purposes
Add non-allowable expenses (like client entertaining). Deduct allowable items like capital allowances or R&D relief. The result is your Taxable Total Profits (TTP).
Step 3: Check your rate band
Compare your TTP against the £50,000 and £250,000 limits (adjusted for associated companies if applicable).
Step 4: Calculate the tax
If TTP is £50,000 or less → 19%
If TTP is £250,000 or more → 25%
Between £50,001 and £250,000 → Use 25% and apply marginal relief
Marginal relief formula:
(£250,000 – TTP) × 3/200
Subtract that relief from the 25% tax figure.
Step 5: Report and pay
Pay within 9 months and 1 day of your year-end. File your CT600 Corporation Tax return online.
Worked example: XYZ Ltd
Taxable profits: £80,000
Main rate: 25% × £80,000 = £20,000
Marginal relief: (£250,000 – £80,000) × 3/200 = £2,550
Final tax due: £20,000 – £2,550 = £17,450
Effective tax rate: 21.81%
XYZ Ltd benefits from marginal relief, reducing the tax below the full 25% rate.
Tax planning tips for small companies
Use these tips to reduce your tax bill in legal ways:
1. Use the Annual Investment Allowance (AIA)
Buy equipment or assets? You can claim 100% capital allowance on qualifying items, up to £1 million.
2. Pay yourself efficiently
A mix of salary and dividends can reduce both Corporation Tax and personal tax.
3. Claim business expenses fully
Ensure you claim all allowable costs—home office, mileage, mobile, software, and subscriptions.
4. Consider R&D relief
If your business works on innovative products or systems, even small companies can claim enhanced deductions.
5. Make pension contributions
Employer pension contributions are a tax-deductible expense and reduce your TTP.
6. Use losses wisely
Trading losses can be carried forward or backward to offset profit, reducing your tax.
7. Time income and expenses
Move expenses into this year and defer income if you’re nearing a tax threshold to stay in the lower band.
Conclusion
Small companies don’t need complex tax teams to stay compliant. By understanding the 2025 tax bands, applying marginal relief, and using smart planning tactics, you can reduce your Corporation Tax bill while staying on HMRC’s good side. If your profits change significantly or you gain an associated company, review your position quickly—it could shift your tax band and increase your bill.
Need Expert Help?
Tax rules can feel overwhelming, but you don’t have to handle them alone. At etax filing, we specialise in helping small businesses across the UK calculate and file their Corporation Tax returns with accuracy and confidence.
✅ Clear advice
✅ Full compliance with HMRC
✅ Quick turnaround
✅ Fixed, affordable fees
Email us today at admin@etaxfiling.co.uk to get started. One email now could save you hundreds later.
If you would like further assistance with this or anything else, please get in touch, contact us for expert assistance.
