Self-employed expenses you can claim in the UK, and what you can't
You pay tax on your profit: what you took in minus the costs of running the business. Every allowable cost you record lowers the profit, so it lowers the tax and the Class 4 National Insurance too. This is the list GOV.UK gives, in plain terms.
What you can claim
- Office costs: stationery, phone and internet for the business.
- Travel: fuel, parking, train and bus fares for business trips (not your normal commute).
- Clothing: uniforms and protective clothing, not everyday clothes.
- Staff and subcontractors: wages, and fees you pay to other people.
- Stock and materials: goods you buy to resell, or raw materials.
- Financial costs: business insurance and bank charges.
- Premises: heating, lighting and business rates for a workspace.
- Marketing: advertising and website costs.
- Subscriptions to trade or professional journals, and training directly related to your work.
What you can't claim
- Any expenses at all if you use the £1,000 trading allowance instead. Which is better?
- Money you take out of the business for yourself.
- The personal share of a cost you use for both business and home. Only the business share counts.
Vehicles and working from home
For a car or van you can claim either the actual running costs or a flat rate per business mile, not both. The flat rate is simpler and needs a mileage log: date, journey, miles. The mileage allowance calculator compares the two for your year. If you work from home you can claim a reasonable share of heating, electricity, and phone and internet, or use HMRC's simplified flat rate; GOV.UK has the amounts.
Keep the records as you go
HMRC can ask for your records, and a penalty applies if they are incomplete. For each cost keep the receipt or invoice and note the date, the amount and what category it falls in. Doing that monthly takes minutes; doing it the week before 31 January takes an evening, and some costs get forgotten.
If you want a ready-made place for it, the SortedDesk Self Assessment Spreadsheet is a one-off £4.99: income and expenses sorted into the return's boxes, with a mileage log built in. For a log on its own there's the HMRC Mileage Log Spreadsheet. Nothing here sends anything to HMRC.
Next: see what your profit comes to in tax. This is a planning guide, not tax advice. List from GOV.UK, read 21 October 2026.