Allowable expenses reduce your taxable profit — and therefore your tax bill. If you're a sole trader earning £40,000 and you correctly claim £8,000 in allowable expenses, you only pay tax on £32,000. At the 20% basic rate plus National Insurance, that's a saving of over £2,000. Most sole traders underclaim because they're unsure what HMRC permits. This guide gives you the full picture.
HMRC's Definition of an Allowable Expense
HMRC permits you to deduct expenses that are incurred "wholly and exclusively for the purposes of the trade." This is the fundamental test. If a cost is purely business-related, it qualifies. If it has a personal element — even a small one — it generally doesn't, unless you can clearly apportion the business portion.
The test sounds simple but it catches people out. A meal taken while working late isn't allowable (eating is a personal need). A client entertainment lunch isn't allowable either (HMRC specifically excludes business entertainment). A £500 course that directly improves your ability to do your current job is allowable; a course that qualifies you for a different career is not.
Office and Administration Costs
If you rent office space, you can deduct the full cost. You can also claim:
- Business phone calls and internet (the business portion, if shared with personal use)
- Stationery, printer ink, and postage
- Computer software subscriptions (accounting software, design tools, project management platforms)
- Business bank charges and card fees
- Trade magazines and professional journals
Working from Home
If you work from home — even part of the time — you can claim a portion of your household costs. HMRC offers two methods:
Flat Rate (Simplified Expenses)
HMRC's flat rate method requires no record-keeping beyond the number of hours you work from home per month:
| Hours worked at home per month | Monthly flat rate |
|---|---|
| 25 to 50 hours | £10 |
| 51 to 100 hours | £18 |
| 101 hours or more | £26 |
This is simple but often underestimates the true cost, particularly if you have a dedicated home office.
Actual Cost Method
You calculate the business proportion of your home's running costs: mortgage interest (not capital repayment) or rent, council tax, electricity, gas, and broadband. You apportion these costs based on the number of rooms used for business and the number of hours used for work.
For example: if your home has 5 rooms and you use one as an office, and you work 8 hours a day in a 24-hour day, the business proportion might be: 1/5 rooms × 8/24 hours = approximately 6.7%. Apply that percentage to your total eligible household costs. If those costs total £15,000 per year, your allowable deduction would be around £1,000.
Caution: if you use a room exclusively for business, HMRC may argue there is a Capital Gains Tax implication when you sell your home (the private residence relief that normally protects homeowners from CGT may be partially denied). Many home-working sole traders deliberately avoid exclusive use to preserve this relief.
Travel and Vehicles
Business travel is allowable. Commuting — the journey between your home and a fixed place of work — is not. For sole traders with no fixed workplace, almost all travel can be argued as business travel.
Mileage Rates (Simplified Expenses)
If you use your personal car for business journeys, the simplest method is HMRC's approved mileage rate:
| Vehicle Type | First 10,000 miles | Above 10,000 miles |
|---|---|---|
| Cars and vans | 45p per mile | 25p per mile |
| Motorcycles | 24p per mile | 24p per mile |
| Bicycles | 20p per mile | 20p per mile |
Keep a mileage log with the date, start and end points, purpose, and distance for every business journey. This is essential evidence if HMRC ever asks questions.
Actual Vehicle Costs
Alternatively, you can claim the actual running costs of your vehicle — fuel, insurance, servicing, repairs, MOT, road tax — apportioned by the ratio of business miles to total miles. You can also claim capital allowances on the purchase price of the vehicle. In practice, the mileage rate method is simpler and often more tax-efficient for lower-mileage drivers.
Other Travel Costs
Train tickets, bus fares, parking charges, and taxi fares for business journeys are all allowable. Hotels and accommodation on genuine business trips are allowable, as are meals on overnight stays (though day-to-day meals are not).
Equipment and Technology
Equipment and technology purchased for the business can be claimed in full in the year of purchase using the Annual Investment Allowance (AIA). The AIA limit for sole traders is currently £1,000,000 — far beyond what most sole traders will spend. In practice, this means you can deduct the full cost of laptops, cameras, tools, machinery, office furniture, and similar equipment in the year you buy them.
If you use an item for both business and personal purposes (like a laptop), you can only claim the business-use proportion.
Marketing and Advertising
All reasonable marketing costs are allowable:
- Website hosting, domain names, and web development fees
- Paid advertising (Google Ads, Meta Ads, LinkedIn)
- Printed materials — flyers, business cards, brochures
- Promotional samples
- Sponsorship of community events (provided it has commercial purpose)
Professional Fees and Services
Fees paid to professionals in connection with your business are allowable:
- Accountancy and bookkeeping fees
- Legal fees for business contracts and disputes
- Architect or surveyor fees for business property
- Recruitment agency fees
Note: legal fees for buying a business property are a capital cost (not a revenue expense) and are treated differently.
Insurance
Business insurance premiums are fully allowable, including:
- Professional indemnity insurance
- Public liability insurance
- Employers' liability insurance (if you have staff)
- Business contents insurance
Personal life insurance or income protection is generally not allowable unless it is structured as a business policy and the business is the beneficiary.
Staff and Subcontractors
If you pay employees or subcontractors, their wages, salaries, and fees are allowable deductions. You can also claim employer's National Insurance contributions, pension contributions (auto-enrolment or otherwise), and the cost of any staff training directly related to their current role.
Training and Development
Training that updates or improves your existing skills is allowable. For example, a plumber attending a course on new regulations, or a graphic designer updating their software skills. Training that qualifies you for a new profession or a fundamentally different kind of work is not allowable — HMRC treats this as capital expenditure on your future earning capacity rather than a current business expense.
What You Cannot Claim
There are some costs that feel business-related but HMRC does not permit:
- Business entertainment: client lunches, staff parties above the trivial benefit limit, sporting events for clients
- Fines and penalties: parking tickets, HMRC late filing penalties
- Personal clothing: clothes you could wear outside work (even if you only wear them for work). Specialist protective clothing, uniforms, and costumes are allowable
- Daily food and drink: unless you're travelling overnight on business
- Personal mobile phone costs: only the business portion of a shared contract
- Drawings: money you take out of the business for personal use is not an expense
Keeping Records
HMRC requires you to keep records for at least 5 years after the 31 January submission deadline of the relevant tax return. This means records from 2024/25 must be kept until at least 31 January 2031. Good record-keeping habits — scanning receipts, keeping bank statements, maintaining a mileage log — protect you in the event of an HMRC enquiry.
Getting It Right
Knowing what you can claim is only half the battle. The other half is having the records to support those claims. Many sole traders overpay tax for years simply through not claiming everything they're entitled to — and it's rarely noticed until an accountant reviews the returns.
At SMD Accountancy, we review every expense category with our sole trader clients to make sure nothing is missed. If you'd like a thorough review of your current tax position or help with your Self Assessment return, book a free 20-minute call with us and let's see what you might be able to reclaim.