Allowable Expenses for the Self-Employed: What You Can (and Can't) Claim

If you're self-employed, knowing your allowable expenses is one of the fastest ways to legally reduce the tax you owe on Self Assessment. Allowable expenses are the everyday costs of running your business - the ones HMRC lets you deduct from your income before working out your profit, and therefore before working out your tax bill. Get this right and you keep more of what you earn. Get it wrong and you either overpay tax out of caution, or claim something you shouldn't and risk a query from HMRC.

This guide walks through what counts as an allowable expense, what doesn't, the most commonly missed categories, and how to keep records that hold up - without ever needing to hand your entire ledger over to a third party just to find out what you owe.

What Are Allowable Expenses?

An allowable expense is a cost that is "wholly and exclusively" for the purpose of your business. That phrase - wholly and exclusively - is the test HMRC applies to almost every claim. If a cost has a genuine business purpose, it's usually allowable. If it's personal, or mixed personal-and-business, only the business proportion is allowable, and you need a reasonable, defensible method for splitting it.

Allowable expenses reduce your taxable profit. So if you invoice £40,000 in a tax year and have £8,000 of allowable expenses, you only pay Income Tax and National Insurance on £32,000 - not the full £40,000. This is separate from any VAT return you may also need to submit if you're VAT-registered; expenses and VAT are tracked differently, though good records serve both. Worth noting: if your total gross trading or miscellaneous income is under £1,000 in a tax year, the trading allowance means you may not need to register for Self Assessment or claim any expenses at all - but once you're earning above that, working out what's genuinely allowable is where the tax savings are.

Common Categories of Allowable Expenses

Office and business premises costs

Rent, utility bills, insurance, and business rates for a dedicated workspace are allowable in full. If you work from home, you can claim a proportion of your household costs - a share of heating, electricity, internet, and council tax based on how much of your home and time is used for business. HMRC also allows a simplified flat-rate method for working from home rather than calculating exact proportions, which suits many sole traders who want less admin: £10 a month if you work from home for 25-50 hours, £18 a month for 51-100 hours, and £26 a month for 101 hours or more. It's a fixed amount regardless of your actual bills, so it's worth comparing against a proportion-of-costs calculation if your home running costs are on the high side.

Travel and mileage

Business travel - trips to see clients, site visits, journeys between different workplaces - is allowable. This does not include your normal commute to a single, regular place of work. Many sole traders use HMRC's simplified mileage rates rather than tracking actual fuel and running costs: currently 55p per mile for the first 10,000 business miles in a car or van each tax year, dropping to 25p per mile after that, with 24p per mile for motorcycles and 20p per mile for bicycles. Choose the mileage rate for a vehicle and you can't also claim separately for fuel, servicing, insurance, or depreciation on that same vehicle - it's one method or the other, applied consistently for as long as you use that vehicle in the business. If mileage is a big part of your business, our mileage tracker logs trips automatically and applies the correct rate without you doing the maths by hand.

Stock, materials, and cost of goods

If you buy or make things to sell, the cost of stock, raw materials, and direct production costs are fully allowable. This is separate from capital items like equipment, which are usually treated differently for tax purposes.

Equipment, tools, and software

Tools, a laptop used for work, software subscriptions, and other equipment needed to do your job are generally allowable, though larger equipment purchases may fall under capital allowances rather than a straightforward expense deduction. Software you use to run your business - including your accounting or invoicing software - is a legitimate, and often overlooked, allowable expense.

Marketing, professional fees, and admin

Advertising, website costs, business cards, accountant or bookkeeper fees, bank charges on a business account, and professional subscriptions relevant to your trade are all allowable. So is the cost of printing and postage for your business.

Staff and subcontractor costs

Wages, subcontractor payments, and employer National Insurance contributions for anyone you employ are allowable business expenses.

Clothing

This one catches people out. Everyday clothing is not allowable, even if you only wear it for work. Uniforms with a company logo, and protective clothing required for the job (steel-toe boots, hi-vis, specialist safety gear), generally are.

What You Cannot Claim

Some costs are explicitly disallowed, even if they feel business-related:

• Client entertainment - meals, drinks, or events for clients are not allowable, even though staff entertainment sometimes is treated differently.
• Personal expenses - anything that is genuinely personal, or the private-use portion of a mixed cost, cannot be claimed.
• Fines and penalties - parking tickets, late filing penalties, and similar fines are not allowable business expenses.
• Your own drawings or salary - as a sole trader, what you pay yourself out of profits is not a business expense; it's a distribution of profit, and it's still taxed as your income.
• Everyday clothing - as above, ordinary clothes worn for work don't qualify just because you wouldn't otherwise buy them.

Simplified Expenses vs Actual Costs

For certain categories - working from home, business mileage, and living on your business premises - HMRC offers simplified flat-rate methods as an alternative to calculating actual costs. Simplified expenses can save considerable admin time, particularly for sole traders with straightforward affairs, but they aren't always the most tax-efficient choice for every business. It's worth comparing both methods, particularly in your first year, to see which gives a fairer reflection of your real costs.

Separately, most sole traders and partnerships (as long as there's no corporate partner involved) now use the cash basis by default, recording income and expenses when money actually arrives or leaves rather than when you raise or receive an invoice. There's no turnover threshold on eligibility any more, so it applies whatever you earn - though limited companies still can't use it and must use traditional accruals accounting instead. Cash basis tends to make expense tracking simpler day to day, since what you've paid out is what you claim, without adjusting for invoices raised but not yet settled.

Records: What HMRC Actually Expects

You don't need to submit receipts with your Self Assessment return, but you do need to keep evidence to support every expense you claim, in case HMRC asks. In practice that means:

• Keeping receipts, invoices, and bank statements for at least five years after the 31 January online filing deadline for the relevant tax year
• Recording the business purpose of each cost, especially for anything with a mixed personal/business element
• Keeping a consistent, contemporaneous log for mileage rather than reconstructing it later

This is where a lot of sole traders lose time - and where poor habits create real risk. Shoeboxes of paper receipts fade, get lost, or simply never get logged. WDI Billing's document ingestion lets you photograph or forward a receipt and have the details captured automatically, with AI-assisted categorisation entirely optional - it works perfectly well without it too. Either way, the record stays in your own account, under your control, ready if you or your accountant ever need it.

Allowable Expenses and Making Tax Digital

As Making Tax Digital extends to more self-employed people, the pressure to keep digital, categorised records of income and expenses throughout the year - rather than reconstructing everything at Self Assessment time - only grows. That doesn't mean your data has to live somewhere out of your control. WDI Billing's Prepare mode lets you keep digital records and prepare everything MTD will eventually require, while you decide when anything is actually sent - nothing streams to HMRC automatically. You press file. For the mechanics of quarterly submissions once you're in scope, see our guide to MTD quarterly updates.

A Simple Way to Stay on Top of Expenses

The best defence against a stressful Self Assessment deadline is capturing expenses as they happen, not months later. That's exactly what our expense tracker app is built for: snap a receipt, log a cost, and let it sit correctly categorised and ready, whether you're a sole trader claiming home-working costs or a growing business with dozens of monthly transactions. If mileage is a regular cost for you, pair it with our dedicated mileage tracker so both categories are covered without duplicate effort.

Start Tracking Your Allowable Expenses Properly

You don't need to hand your books over to anyone to get this right - you just need a system that captures every allowable expense as it happens and keeps the evidence in one place, under your control. WDI Billing runs on Records, Prepare, and File modes so you decide exactly when anything reaches HMRC, and your data stays yours throughout. See our pricing and start a free trial to bring your expense tracking - and your Self Assessment prep - under control today.