What Expenses Are Tax Deductible for Small Businesses?

Running a small business comes with plenty of costs — but the good news is that many of them can be deducted from your taxable profits. Understanding which expenses qualify as allowable can help reduce your tax bill and improve your cash flow.

This guide explains what HMRC considers a tax-deductible business expense, and how to make sure you’re claiming everything you’re entitled to.

Understanding Tax-Deductible Business Expenses

HMRC allows businesses to deduct the costs that are “wholly and exclusively” for business purposes.
This means the expense must be directly related to running your business — not personal use.

By claiming these allowable costs, you can lower your taxable profits, reducing the amount of Income Tax (if you’re self-employed) or Corporation Tax (if you operate a limited company) that you owe.

You can find HMRC’s full definition of allowable expenses on GOV.UK.

Common Deductible Expenses for Small Businesses

Here are some of the most common expenses that small businesses can usually claim:

• Office costs – Rent, utilities, internet, phone bills, and stationery or office supplies.

• Travel – Business travel costs including fuel, train fares, parking, and accommodation when required for work.

• Vehicle expenses – If you use a car or van for business, you can claim mileage or a proportion of running costs.

• Staff costs – Salaries, bonuses, National Insurance, and pension contributions.

• Professional fees – Accountancy, legal, consultancy, and professional memberships related to your trade.

• Marketing and advertising – Website costs, social media ads, and promotional materials.

• Insurance – Business, professional indemnity, or public liability insurance.

• Training – Courses or certifications relevant to your current business.

• Stock and materials – Goods purchased for resale or production.

Each business is different, so always consider whether the expense is genuinely necessary for running yours.

Home Office Expenses (for the Self-Employed)

If you run your business from home, you can claim a portion of your household bills — such as heating, electricity, and broadband — as business expenses.

You can either:

• Use HMRC’s simplified flat-rate method, based on the hours you work from home each month, or

• Claim a proportion of actual household costs, based on usage and space.

For full details, see HMRC’s guidance on simplified expenses.

How to Maximise Your Deductions

Good record-keeping is the key to maximising your allowable expenses and avoiding mistakes. HMRC expects clear evidence to support every claim.

To stay compliant and efficient:

1. Keep detailed records – Save all invoices, receipts, and bank statements.

2. Track mileage and travel logs – Record journeys, dates, and purposes.

3. Use accounting software – Tools like Xero or QuickBooks make it easier to categorise and record expenses.

4. Separate business and personal spending – Use a dedicated business bank account to simplify reporting.

5. Review your expenses regularly – Don’t wait until year-end; this prevents missed claims.

For official information on claiming expenses, visit HMRC’s guidance for the self-employed.

When to Get Professional Advice

Some expense areas — such as home use, vehicles, or staff benefits — can be complex.
Working with a qualified accountant ensures you:

• Claim every deduction you’re entitled to,

• Stay compliant with HMRC rules, and

• Avoid over- or under-claiming.

At Merranti Accounting, we help small businesses manage their expenses efficiently and plan ahead to reduce their overall tax burden.