One of the most effective ways to reduce your Self Assessment tax bill as a sole trader is to claim every allowable expense you are entitled to. Many sole traders either under-claim — missing legitimate deductions — or over-claim — including personal costs that HMRC does not allow. Both are a problem.
This guide covers every major category of allowable expense for 2025/26, with practical examples and HMRC's rules explained plainly.
The Golden Rule: "Wholly and Exclusively"
HMRC allows you to deduct expenses that are incurred wholly and exclusively for the purposes of your trade. This phrase is the foundation of everything. If an expense has a personal element — even partly — HMRC may disallow it unless it can be clearly apportioned.
There are some important exceptions and simplifications, which we explain in each category below.
Office and Home Working Costs
If you work from home, you can claim a proportion of your household costs. HMRC offers two methods:
Flat Rate (Simplified Expenses)
| Hours worked at home per month | Monthly flat rate |
|---|---|
| 25 – 50 hours | £10 |
| 51 – 100 hours | £18 |
| Over 100 hours | £26 |
Actual Cost Method
Alternatively, you can calculate the actual proportion of your home costs attributable to business use. You apportion by the number of rooms used for business and the hours used. This requires records but can result in a larger deduction.
Allowable household costs include: mortgage interest (not capital), rent, council tax, utilities, insurance, and broadband — all on an apportioned basis.
Travel and Vehicle Costs
Travel for business purposes is allowable. Travel between your home and a permanent workplace is not — that is a commute, which HMRC treats as personal.
Mileage Allowance
The simplest approach for most sole traders is the HMRC approved mileage rate:
| Vehicle Type | First 10,000 miles | Over 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 |
If you use the mileage rate, you cannot also claim actual vehicle running costs (fuel, insurance, servicing). You choose one method and stick with it for that vehicle.
Equipment, Tools, and Capital Allowances
Business equipment — computers, tools, machinery, office furniture — qualifies for capital allowances rather than being deducted as a direct expense. Under the Annual Investment Allowance (AIA), you can deduct 100% of the cost of most plant and machinery in the year of purchase, up to a current limit of £1,000,000.
For smaller sole traders, this means a laptop, desk, or work tools can usually be deducted in full in the year you buy them.
Professional Fees and Subscriptions
Allowable professional fees include:
- Accountancy and bookkeeping fees
- Legal fees relating to your business (not personal legal matters)
- Membership of professional bodies and trade associations relevant to your work
- Professional indemnity insurance
- Bank charges on your business account
Training and Professional Development
Training costs are allowable if they are to update or maintain existing skills relevant to your current trade. They are not allowable if they enable you to start a new trade or gain new skills in a different area.
A self-employed electrician attending a course on new wiring regulations — allowable. The same electrician attending a plumbing course — not allowable, as it enables a new trade.
Phone and Broadband
If you have a dedicated business phone or broadband contract, the full cost is allowable. If you use your personal phone or home broadband for business, you can claim the business proportion only. Keep a record of how you calculate the split.
Clothing
Protective clothing required for your work (hard hats, safety boots, high-visibility jackets) is allowable. Ordinary clothing — even if you only wear it for work — is generally not allowable, as it serves a personal purpose (warmth and decency). Uniforms with a permanent company logo are an exception.
Food and Subsistence
Meals are generally not allowable for sole traders unless you are on a qualifying business trip away from your normal place of work. HMRC does not allow the cost of your normal daily meals, even if you work from home or are busy.
Common Mistakes to Avoid
- Claiming personal phone or internet bills in full — only the business proportion is allowable
- Not keeping receipts — HMRC can ask for evidence up to 5 years after the filing deadline
- Claiming client entertaining — HMRC does not allow the cost of entertaining clients or customers
- Confusing capital and revenue expenditure — buying a new laptop is capital expenditure, not a direct expense; it goes through capital allowances
- Not using simplified expenses — for vehicles and home working, HMRC's flat rates are often simpler and the outcome comparable
See HMRC's full guidance on expenses if you are self-employed and simplified expenses.
General information only. This article provides general guidance on UK tax and accounting matters and reflects our understanding of legislation and HMRC guidance at the time of publication. Tax rules, rates, and thresholds change frequently. Nothing in this article constitutes personalised tax or financial advice. Always seek advice specific to your circumstances from a qualified accountant before taking action. Ledgertech Accountants Ltd accepts no liability for any loss arising from reliance on this content.
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