How to keep expenses as a sole trader: a simple system that works

Why keeping good expense records saves you real money

Every pound you spend on genuine business expenses directly reduces your taxable profit. If you are a sole trader paying the basic 20% income tax rate plus 9% Class 4 National Insurance (6% above £50,270), that is a 29% saving for every pound of legitimate expense you claim. Consider this: on £10,000 of genuine business expenses, that is £2,900 you keep rather than hand to HMRC. The impact is significant, especially when margins are tight.

Yet, many self-employed tradespeople do not keep track properly. They might have a rough idea of what they spend but cannot tell you within £500 what their fuel costs, material purchases, or tool costs were last year. When Self Assessment time comes, they either miss expenses they could have claimed or spend days digging through bank statements trying to remember what transactions were for. This inefficiency not only costs money but also time, which could be better spent growing your business or honing your trade skills.

What expenses to track

For a self-employed tradesperson, claimable business expenses typically include:

• Materials and consumables used on jobs
• Tools and equipment (either as an expense or capital allowance)
• Vehicle costs (fuel, servicing, insurance, MOT, breakdown cover) — either actual costs or HMRC mileage rate of 45p per mile for the first 10,000 miles
• Van purchase (through Annual Investment Allowance)
• Work clothing and PPE (not ordinary clothing, only functional protective items)
• Phone bill (business proportion)
• Business insurance (public liability, tools, employers liability)
• Training and qualifications directly related to your trade
• Professional fees (accountant, invoicing software)
• Advertising and marketing costs
• Bank charges on your business account

It is important to remember that not all expenses are straightforward. For example, when claiming vehicle expenses, you must decide between actual costs and mileage. Each has its pros and cons depending on your specific circumstances. If you drive a lot of miles, the mileage rate might be more beneficial. Conversely, if your vehicle costs are high, actual expenses could save you more. Understanding these subtleties can make a big difference in how much you save come tax time. For a full breakdown, see our guide to allowable expenses for self-employed tradespeople.

The simplest system that actually works

You do not need expensive software or a complex spreadsheet. The basics are: capture every business purchase at the time it happens, categorise it, and store the receipt or evidence. Here is a system that takes less than 5 minutes a day:

1. Open a separate business bank account. Put all business income in and pay all business costs from it. This one step makes your records enormously cleaner. Starling, Monzo, and HSBC Kinetic all offer free sole trader accounts. Separating personal and business finances not only simplifies tax filing but also helps with cash flow management.
2. Use a simple spreadsheet or app. Log each expense: date, supplier, description, category, amount. Even a basic Google Sheet with columns for each category works fine for most sole traders. Free apps like Receipts by Wave or Money Manager also work well. The key is consistency. If you log expenses regularly, you prevent them from piling up into an overwhelming task.
3. Photograph receipts immediately. Use your phone's camera and store them in a folder on Google Drive or Dropbox. Paper receipts fade and get lost. A photo is accepted by HMRC as a valid record. This simple action ensures you always have a backup and can avoid the frantic search for missing paperwork at the end of the year.
4. Reconcile monthly. At the end of each month, cross-check your spreadsheet against your bank statement. Catch anything you missed while the memory is fresh. Regular reconciliations prevent small errors from becoming significant discrepancies over time.

When to use invoicing and expense software

A spreadsheet works well until your income grows and transactions become numerous. Once you are dealing with 30 or more transactions a month, dedicated software pays for itself in time saved. InvoiceAdept lets you scan receipts, track expenses by category, create invoices, and keep MTD-ready records automatically. It is built specifically for UK tradespeople and sole traders — no accountant jargon, no unnecessary complexity. Software not only saves time but also reduces the risk of errors that can occur from manual data entry.

Making Tax Digital for Income Tax (MTD ITSA) requires sole traders with income over £50,000 to submit quarterly updates digitally from April 2026, and those with income over £30,000 from April 2027. The earlier you move to a digital system, the less disruptive the transition will be. Traditional paper-based systems will simply not suffice under the new regulations. Transitioning early allows you to become comfortable with the new processes before they become mandatory. See our guide to MTD for sole traders for more detail.

How long to keep records

HMRC requires sole traders to keep records for at least 5 years after the 31 January submission deadline for the relevant tax year. For a 2025/26 tax return filed in January 2027, keep those records until at least January 2032. Records can be digital. Store them somewhere with a backup — cloud storage like Google Drive is ideal. This ensures that even in the event of a computer failure or physical damage to your records, your data remains safe and accessible. Additionally, having digital records makes it easier to provide evidence in case of an HMRC audit.

The most common expense mistakes

The most common expense mistakes sole traders make include claiming personal costs as business expenses. HMRC investigates this and it can lead to penalties. It is essential to maintain a clear distinction between personal and business expenses. Another mistake is missing genuine claimable costs because there was no receipt. Make it a habit to request a receipt for every business transaction. Not claiming vehicle mileage because it seems complicated is also a frequent error. However, it is not complicated — the free mileage calculator does the work for you. Lastly, leaving expenses until Self Assessment time instead of tracking them monthly can lead to missed deductions and a stressful experience. Fix these habits and your tax bill will fall while your records will be cleaner.

Understanding Capital Allowances

When purchasing substantial items like vans or expensive tools, you might ask whether these can be expensed immediately. This is where capital allowances come into play. Instead of deducting the full cost of an asset in the year you purchase it, capital allowances let you spread the deduction over several years. The Annual Investment Allowance (AIA) allows you to deduct the full cost of certain assets up to £1 million per year, offering a significant benefit for those making substantial investments in their business equipment.

Understanding the difference between capital expenditures and revenue expenditures is key. Capital expenditures provide benefits beyond the current tax year, such as buying a new van or machinery. In contrast, revenue expenditures are costs incurred in the day-to-day running of the business, like fuel or materials. Properly categorising these can impact your tax planning strategy.

When to seek professional advice

While many sole traders handle their own accounts, there comes a point when professional advice can be invaluable. If your business is growing, or if your financial situation is becoming more complex, consulting with an accountant can save you money in the long run. Accountants are not just for filing taxes; they can offer strategic advice on how to structure your business, maximise deductions, and plan for future growth.

For example, an accountant might advise on the benefits of registering for VAT if your turnover is nearing the £85,000 threshold. They can also provide insights on pension contributions, which not only reduce your taxable income but also prepare you for retirement. By understanding your specific business needs and goals, an accountant can tailor advice to help you succeed.