Self-Employed Expenses — The Complete Allowable Expenses Guide (2025)
The difference between a profitable business and an unnecessarily large tax bill often comes down to one thing: knowing what you can and cannot claim. HMRC allows a wide range of business expenses — but the rules are specific and the 'wholly and exclusively' test catches out many sole traders. This comprehensive guide covers every major expense category with real examples.
Why Getting Your Expenses Right Matters
Allowable expenses reduce your taxable profit — meaning you pay Income Tax and National Insurance on a smaller figure. Every pound of allowable expenditure you fail to claim costs you money. A higher-rate taxpayer (40%) who misses £5,000 of allowable expenses pays an extra £2,000 in unnecessary tax. This guide covers every major expense category HMRC allows — and the traps that catch people out.
The Golden Rule — "Wholly and Exclusively"
The fundamental test for any self-employed expense is whether it was incurred "wholly and exclusively for the purposes of the trade" — the wording from section 34 of the Income Tax (Trading and Other Income) Act 2005. HMRC applies this test strictly. If an expense has a dual purpose (partly personal, partly business), the default position is that none of it is allowable. However, where a specific part of the cost is identifiably business-related, that portion can be apportioned and claimed.
Every Major Expense Category — What You Can Claim
If you work from home, you can claim a proportion of heating, electricity, broadband, and council tax based on the number of rooms used for business and time spent working. Or use HMRC's simplified flat rate: £10/month (25–50 hrs), £18/month (51–100 hrs), £26/month (101+ hrs).
Claim 45p per mile for the first 10,000 business miles per year, then 25p per mile (HMRC Approved Mileage Allowance Payments). Commuting to a regular place of work is not allowable — only travel to clients, suppliers, or temporary work locations. Keep a mileage log.
If you use your personal mobile for business, claim the business-use proportion of your bill. A dedicated business phone is fully allowable. Broadband: if used partly for business, claim the business proportion only.
Laptops, computers, printers, cameras, and other equipment used for business can be claimed. If purchased outright, claim through capital allowances (Annual Investment Allowance) — up to £1 million per year can be written off immediately. Software subscriptions are a trading expense (not capital) and are fully deductible.
Courses, books, professional journals, and training that update existing skills or knowledge relevant to your trade are allowable. Training to acquire a new skill for a new trade is capital expenditure — not deductible. The boundary can be fine: a plumber learning electrical skills = new trade; a plumber attending a safety refresher = allowable update.
Accountant's fees, solicitor's fees for business matters, professional membership subscriptions (if relevant to your trade), and indemnity insurance are all fully allowable. Personal tax return preparation fees are allowable if you are in business.
Website costs, Google Ads, social media advertising, printed materials, trade show stands, and business cards are all allowable. Client entertainment — taking a client to dinner or a sporting event — is explicitly not allowable under section 45 ITTOIA 2005, even if the meal is only about business.
Professional indemnity insurance, public liability insurance, product liability insurance, and business contents insurance are all fully deductible. Personal life insurance or critical illness cover is not a business expense — even if losing your ability to work would damage the business.
Travel to client sites, temporary work locations, and business conferences is allowable — including train fares, flights, taxis, and parking. Hotel costs for overnight business stays are allowable. The trip must be for genuine business purposes. If you extend a business trip for personal reasons, only the business element is deductible.
Specialist protective clothing (safety boots, hi-vis jackets, hard hats) and uniforms bearing a company logo are allowable. "Smart" clothing bought to wear at client meetings is not — even if you would not otherwise buy it. The test is whether the clothing could be worn outside of work.
You can claim the cost of a meal while travelling away from your normal place of work on a business journey — but not your regular lunch at your desk. The meal must be on a trip that is not your normal daily commute and the cost must be reasonable. Client entertainment meals are not allowable (see Marketing above).
Business bank account charges, merchant services fees, and interest on business loans or overdrafts are allowable. Interest on a personal loan used to fund the business may also be allowable. Interest on the purchase of a capital asset (such as a van) is a revenue expense, deductible separately from the capital allowance on the asset itself.
Capital Allowances — Big Purchases
Capital expenditure — money spent on assets that will be used in the business over a number of years, such as machinery, vehicles, and equipment — is not deducted as a trading expense but instead qualifies for capital allowances. The most important are:
- Annual Investment Allowance (AIA) — allows 100% of the cost of qualifying plant and machinery to be deducted in the year of purchase, up to £1 million per year. Almost all small business capital purchases fall within the AIA limit.
- Writing Down Allowance (WDA) — where the AIA limit is exceeded, the remainder enters a "pool" and is written down at 18% per year (main rate) or 6% per year (special rate for long-life assets and integral features).
- First Year Allowances — 100% allowance in the year of purchase for certain qualifying assets, including electric vehicles and energy-efficient plant.
The Trading Allowance — For Very Small Income
If your total gross self-employment income is £1,000 or less in a tax year, you do not need to declare it or pay any tax — this is the trading allowance. If your income is between £1,000 and a modest figure where actual expenses exceed £1,000, you can choose to deduct the £1,000 trading allowance instead of actual expenses — whichever gives you the lower taxable profit. You cannot use both the trading allowance and actual expenses in the same year.
The Flat Rate Scheme for Home Workers
Rather than calculating the exact business proportion of home running costs, HMRC allows self-employed people to use simplified flat rate deductions for working from home:
| Hours worked per month | Flat rate per month |
|---|---|
| 25 to 50 hours | £10 |
| 51 to 100 hours | £18 |
| 101 hours or more | £26 |
These rates are modest. If you have significant home running costs and work from home full-time, calculating the actual proportion may give you a larger deduction. Run the numbers both ways.
Expenses You Cannot Claim
- Client entertainment — meals, drinks, events, gifts over £50 per person per year. Explicitly disallowed under s.45 ITTOIA 2005.
- Fines and penalties — parking fines, HMRC penalties, court fines. These are not incurred "for the purposes of the trade."
- Commuting costs — travel between your home and a regular, fixed workplace is not allowable.
- Personal expenditure — even where you can argue a dual purpose, purely personal costs have no business deduction.
- Capital repayments on loans — only the interest element is deductible, not the capital repayment.