This is the comprehensive classification guide for deciding whether common sole-trader costs are allowable and how they enter taxable profit. The self-employed expense guides page remains the navigation hub for focused guides such as working from home and vehicle mileage; it is not a second version of this article.
The core rule
Only business costs are allowable. If something has business and private use, deduct only a reasonable business share.
An expense reduces taxable profit; it is not repaid in full by HMRC. Keep evidence of amount, date, supplier, business purpose and payment.
Common categories
HMRC categories include office costs, business travel, qualifying clothing, staff, stock and materials, finance and insurance, business premises, marketing and relevant training. Each has detailed conditions.
Ordinary clothing, private travel, drawings, fines and loan capital are examples that do not become allowable merely because paid from a business account.
Mixed costs
Use a supportable measure: itemised calls, business miles, room/time use or another factual basis. Do not choose a round percentage without evidence.
Eligible sole traders and partnerships without a corporate partner may use simplified flat rates for qualifying vehicles, working from home and living at business premises. Other costs still use actual amounts. Apply one permitted method consistently and keep the required mileage, hours or occupancy records. The focused homeworking expenses guide compares actual household costs with the flat-rate method.
Trading allowance
The trading allowance can replace actual and simplified expenses for eligible income. It cannot be claimed as an extra £1,000 on top of those costs, and capital allowances cannot also be claimed for the same trading income.
Compare gross receipts minus actual allowable expenses with gross receipts minus the available allowance. Apply exclusions before choosing.
Capital items
Equipment treatment depends on the accounting basis. Under traditional accounting, qualifying equipment and business vehicles can require capital allowances. Under cash basis, most items kept for the business are claimed as ordinary allowable expenses, but cars remain within capital allowances.
Classify the item and accounting basis rather than treating every payment as a day-to-day cost.
Category checks
Travel: business journeys can qualify; ordinary commuting and private travel do not.
Clothing: uniforms and protective clothing can qualify; ordinary clothing does not.
Training: updating skills for the existing trade can qualify; training to start a new unrelated trade may not.
Professional costs: business accountancy, legal and insurance costs can qualify, but preparing the personal Self Assessment return is restricted.
Stock: record purchases, returns and stock treatment under the accounting basis.
Evidence workflow
- Capture the invoice or receipt.
- Record business purpose.
- Remove private use.
- Decide revenue, capital or disallowable.
- Map to the return category.
- Reconcile bank and records.
- Preserve the calculation.
Apportionment example
Suppose a phone bill contains identifiable business calls and private use. Preserve the itemised statement, identify the business element and claim only that supportable share. If a broadband or premises bill cannot be itemised in the same way, use a reasonable method connected to actual business use and record how it was calculated. The method should be capable of being repeated from the retained evidence.
The fact that a cost helped the owner work does not automatically make the whole payment allowable. A bank statement proves payment but not business purpose, and an invoice proves what was bought but not how it was used. Keep both where available and add a short contemporaneous note for unusual items.
At year end, reconcile expense categories to the accounts and the Self Assessment figures. Investigate duplicates, personal transfers and capital purchases before submission. If the trading allowance is being considered, calculate the result under each permitted approach and keep the comparison; do not enter the allowance and the same actual expenses together.
Use the sole trader tax guide for the same-wave overview of how the resulting profit feeds into registration, filing and payment duties.
Common mistakes
- Claiming the whole mixed bill.
- Deducting personal drawings.
- Combining trading allowance and expenses.
- Claiming ordinary clothing.
- Treating capital assets as routine supplies.
- Keeping receipts without a business-purpose record.
What to do next
- Review every category against HMRC guidance.
- Document apportionment.
- Compare simplified methods.
- Separate capital purchases.
- Reconcile to turnover and bank records.
- Retain source evidence.