Allowable expenses for the self-employed

How allowable expenses reduce tax

Self-employed traders pay Income Tax and National Insurance on taxable profit, not on gross turnover. Allowable expenses are business costs that HMRC permits to be deducted when calculating that profit. A lower profit figure reduces the tax bill and, in turn, can reduce payments on account in following years once the return is processed.

The deduction is claimed on the Self Assessment return, normally within the self-employment pages (SA103 or the equivalent online sections). Each category of spending must be supportable if HMRC asks questions during a compliance check. Estimates without a reasonable basis, or figures rounded from memory years later, carry risk even when the underlying spending was genuine.

Expenses are not the same as capital allowances. Equipment with a lasting benefit — such as a laptop, van, or shop fitting — may be treated as capital expenditure and relieved through capital allowances rather than as a straight annual expense. Day-to-day running costs, by contrast, are usually revenue expenses deducted in the year they are incurred.

The wholly and exclusively rule

The central test for most revenue expenses is that the cost was incurred wholly and exclusively for business purposes. This phrase appears throughout HMRC guidance and case law. A payment that serves both a private and a business purpose — a family holiday that includes one client meeting, or a suit worn outside work — generally fails the test and cannot be deducted, even in part.

The rule is stricter than "mainly for business." HMRC does not permit apportioning a clearly dual-purpose item by guesswork. Where a cost genuinely mixes business and private use, only the business element may be deductible if it can be identified and calculated on a reasonable basis. Motoring is the most familiar example: business mileage can be claimed, but private journeys cannot.

Fixed costs that support both life and work in a shared space — such as rent, council tax, or domestic electricity — require a clear apportionment method for the business share. HMRC expects the method to be logical, consistent, and applied each year unless circumstances change. Arbitrary percentages without supporting analysis are difficult to defend.

Personal drawings, the proprietor's own wages in sole trader accounts, and income tax payments are never allowable. Repayments of business loans are not expenses either, though interest on those loans may be.

Common categories of allowable expenses

HMRC groups typical sole trader costs into recognisable headings. The list below reflects categories commonly seen on returns and in GOV.UK guidance. Not every item will apply to every trade.

Office and premises costs include rent for business premises, business rates, utility bills for a dedicated office, stationery, printing, and postage. Software subscriptions used solely for the business, cloud storage for work files, and telephone lines dedicated to trading fall here as well.

Travel and subsistence covers transport between workplaces (not ordinary commuting from home to a regular base), parking, tolls, public transport for business journeys, and reasonable accommodation and meals on overnight business trips. The cost of running a vehicle for business — fuel, insurance, servicing — can be claimed using actual costs apportioned by business use, or through simplified mileage rates.

Staff costs cover salaries, employer National Insurance, pension contributions, and agency fees for employees or subcontractors who are treated as employees. Payments to genuine freelancers for specific jobs are usually recorded as subcontractor costs rather than wages.

Stock and materials include goods bought for resale, raw materials, and direct production costs. The figure on the return should reflect opening stock, purchases, and closing stock at the year end.

Financial costs include bank charges on a business account, interest on business loans and overdrafts, hire purchase interest, and card processing fees on sales. Late payment penalties and fines are not allowable.

Marketing and professional fees cover advertising, website costs, professional indemnity insurance, accountancy fees, and legal advice related to the business. Membership of a professional body relevant to the trade is often deductible; purely social club membership is not.

Training is allowable when it updates skills used in the current business. Training for a new trade or qualification that opens a different line of work is normally treated as personal investment and is not deducted against existing profits.

Working from home

Many sole traders work partly or wholly from home. HMRC allows a deduction for the business proportion of household costs — typically heating, electricity, council tax, mortgage interest or rent, insurance, and internet — when a room or area is used for work.

The actual-cost method requires calculating the total household bill and apportioning by floor area, time spent working at home, or a combination of both. A room used exclusively as an office for most of the week supports a higher proportion than a kitchen table cleared once a day. Consistency year to year matters; switching methods without reason can invite questions.

HMRC's simplified expenses scheme offers a flat rate for working from home based on hours worked there each month. The rates are modest and suit traders with low household costs or those who prefer minimal record-keeping. Traders with significant dedicated space or high utility bills often achieve a larger deduction using actual costs, but only if the apportionment is documented.

Neither method permits deducting the full cost of domestic living. The private element of home life remains private, and HMRC's manuals stress that creating a dedicated office does not make the entire property a business expense.

Simplified expenses for vehicles and premises

Beyond home working, simplified expenses cover business mileage and, in limited cases, living at business premises such as a guest house where the proprietor resides on site.

For vehicles, HMRC publishes per-mile rates for cars, vans, and motorcycles. The trader chooses simplified mileage for a vehicle or actual costs — not both for the same vehicle in the same year. Once simplified mileage is used for a car, continuing with it for that car is expected in later years unless actual costs are adopted consistently going forward.

Simplified mileage does not include interest on vehicle finance, which may be claimed separately in some circumstances. Parking, congestion charges, and tolls on business journeys can be added on top of the mileage rate.

Living at business premises uses a flat monthly deduction based on the number of people living there, with a cap related to personal living costs. This niche applies to traders such as publicans or carers living where they work; it is not a general substitute for home-working claims.

Comparing simplified and actual figures before filing is worthwhile when records are good. The sole trader Self Assessment guide situates these choices within the wider picture of turnover, profit, and Class 2 and Class 4 National Insurance.

Evidence and record-keeping

HMRC does not require every receipt to be submitted with the return, but records must exist to substantiate each figure if asked. The general retention period is five years after the 31 January filing deadline for the relevant tax year.

Useful evidence includes sales and purchase invoices, receipts, bank and card statements showing business transactions, mileage logs with dates and purposes, contracts, and apportionment workings for home costs. Digital copies are acceptable if they are readable and stored securely.

Mixed-use bank accounts blur business and personal spending and make reconstruction harder under enquiry. A separate business account is not legally required for sole traders, but it sharply reduces errors and saves time when preparing figures for how to file Self Assessment.

Capital purchases should be recorded with the date of acquisition and description of the asset so capital allowances can be calculated correctly. Blurring capital and revenue — expensing a £2,000 laptop immediately without considering capital treatment — can misstate profit even when the underlying spending was legitimate.

Expenses that are often misunderstood

Certain costs frequently appear on draft returns but fail HMRC's tests or need careful treatment.

Clothing is allowable only for protective gear or uniforms not suitable for everyday wear. Everyday clothing, even if worn only for work, is not deductible. Client entertaining — lunches, tickets, hospitality — is not allowable for Income Tax, though modest staff entertaining may be in specific contexts. Charitable donations are relieved through Gift Aid or the donations box on the return, not as business expenses.

Use of a personally owned car for business requires a defensible mileage log or a clear apportionment of actual running costs. Rounded estimates of "about 40% business use" without odometer readings or journey records are weak under scrutiny.

Costs reimbursed by a client should not be double-counted as expenses if they were already included in turnover. Similarly, personal mobile phone contracts with a nominal business use require apportionment rather than deducting the full monthly fee.

Allowable expenses and filing deadlines

Expense figures feed directly into the profit line on the return. Errors or omissions discovered after filing can be corrected through an amendment, but interest and penalties may apply if the result is tax paid late. Aligning expense preparation with Self Assessment deadlines avoids filing in haste and overlooking supported deductions.

Payments on account for the following year are based on the declared profit. Under-claiming allowable expenses raises taxable profit unnecessarily and can inflate future instalments. Over-claiming creates the opposite risk — a lower bill now and a larger balancing payment plus interest later if HMRC disagrees.

Your next step

Traders preparing accounts for the tax year should gather records by category before entering figures online or on paper. Comparing simplified and actual methods for motoring and home working takes little time when mileage and household bills are already to hand.

For the wider filing process, the guide on how to file Self Assessment describes how expense totals flow into the return. Sole traders may also read payments on account to see how declared profit shapes January and July tax instalments after the first substantial bill.