Start with a clean picture of your sole trader income

As a sole trader, you and your business are the same legal entity. That makes life simple in many ways, but it also means your personal and business money can blur together if you let it. Keep a separate bank account, even a basic second current account, and use it only for business income and costs. Your tax year runs from 6 April to 5 April. If your self-employed income is more than £1,000 in a tax year, you usually need to tell HMRC and file a Self Assessment tax return. Register in good time — by 5 October after the end of the tax year if you are new to it.

Record every sale, invoice and payment

Income is not just the money that lands in your bank. If you invoice a client in March but they pay in April, the timing depends on your accounting method. Many sole traders use the cash basis, which means you record income when you receive it and expenses when you pay them. It is straightforward, and HMRC allows it for most small businesses. Whatever method you choose, note the date, client, invoice number, amount and what the payment was for. If you are VAT registered, record VAT separately. If you are not, simply keep your invoices clean and numbered.

• Issue a numbered invoice for every job, even a small one.
• Log cash, card and bank transfer payments on the same day.
• Never use the business account for personal spending.
• Keep a note of any grant, refund or other business income.

Know what you can claim as an allowable expense

An allowable expense is a cost that is wholly and exclusively for your business. You can claim it if you have proof and it is not personal, entertaining or a fine. Common claims include stock and materials, tools, stationery, postage, software, accountancy fees, insurance, bank charges, professional subscriptions, and training that updates your existing skills. You can also claim a business proportion of phone, internet, and home office costs such as rent, utilities or council tax. Clothing is only allowable if it is protective or a branded uniform. Client entertaining, gym memberships and ordinary everyday clothes are not.

Bigger purchases such as a laptop, camera or machinery are usually claimed through capital allowances rather than as a normal expense. The annual investment allowance often lets you deduct the full cost in one go, but check the rules. Simplified expenses can help with vehicle costs or a home office. For mileage, you can claim 45p per mile for the first 10,000 business miles in a tax year, then 25p per mile after that. Keep a mileage log with dates, destinations and business purpose.

Keep proof — no receipt, no claim

HMRC does not expect perfection, but it does expect evidence. Keep receipts, supplier invoices, bank statements, contracts and mileage logs. Digital copies are fine if they are clear and complete, so photograph paper receipts as soon as you get them and store them in dated folders. Back up your records somewhere safe. You must keep business records for at least five years after the 31 January deadline for the relevant tax year. For example, keep 2024/25 records until 31 January 2031. If you use the £1,000 trading allowance instead of claiming actual expenses, you still need to keep enough records to show your income is correct.

Build a simple bookkeeping routine

Little and often beats a frantic weekend before the deadline. Set aside twenty minutes each week to file receipts, update your income and expenses, and reconcile your bank account. Once a month, check your profit so far and put aside money for tax — many sole traders set aside 20% to 30% of their profit. Use a simple spreadsheet or bookkeeping software, whichever you will actually keep up. Categories such as sales, materials, travel, office, and professional fees make your year-end figures much easier to prepare. If you are unsure whether something is allowable, note it separately and ask before you claim it.

Get ready for Self Assessment

Your Self Assessment return brings together your income, allowable expenses and any other taxable income. If your tax bill is more than £1,000, HMRC may ask for payments on account towards the next year, due in January and July. The main deadline is 31 January for filing online and paying what you owe. Late filing and late payment both attract penalties, so diarise the date early. Before you file, double-check that your income matches your invoices and bank statements, that every expense has a receipt, and that you have claimed everything you are entitled to. Good records are not just for HMRC — they show you which work is profitable and help you make calmer, better decisions.