Find the money you can keep
UK self-employed tax return builder
Every box on the SA103S self-employment page, in plain words, with the figures worked out for you and nothing invented.
Start with your real figures
The builder starts completely empty. Put in your turnover and your costs and it fills in every box below, works out your Class 4 and Class 2 National Insurance, and shows the payments on account HMRC will ask for. Nothing is saved anywhere unless you are signed in and choose to save it.
The SA103S boxes that matter
These are the boxes almost every sole trader fills in. The builder puts your figures in each one.
| Box | What goes in it | In plain words |
|---|---|---|
| Box 1 | Description of business | What you actually do, in a few words. Plain wording is fine. |
| Box 7 | Accounting period start | Usually 6 April, unless this is your first or last year. |
| Box 8 | Accounting period end | Usually 5 April. HMRC now expects the tax year basis. |
| Box 9 | Cash basis used | Tick if you count money in and out rather than invoices raised. |
| Box 15 | Your turnover | Everything you invoiced or were paid for the work, before any costs. |
| Box 16 | Any other business income | Grants, insurance payouts, scrap sales and similar. |
| Box 17 | Costs of goods bought for resale | Stock and materials that went into what you sold. |
| Box 20 | Car, van and travel expenses | Mileage at 45p for the first 10,000 miles, then 25p. |
| Box 21 | Wages, salaries and other staff costs | Anyone on your payroll, plus subcontractors you paid. |
| Box 22 | Rent, rates, power and insurance | Includes the flat rate for working from home. |
| Box 25 | Accountancy, legal and other professional fees | Your accountant's bill is allowable. |
| Box 27 | Phone, stationery and other office costs | Software subscriptions belong here. |
| Box 31 | Net profit | Turnover less allowable expenses. This is the figure you are taxed on. |
| Box 32 | Net loss | If costs beat income. Losses can often be set against other income. |
| Box 60 | Class 4 National Insurance exemption | Tick only if you are over State Pension age or otherwise exempt. |
| Box 64 to 66 | Any other information | Explain anything unusual before HMRC has to ask. |
Which schedule do you need?
SA103S: Self-employment (short)
Turnover under 90,000 and straightforward accounts. This is the one most sole traders need.
The official form on GOV.UKSA103F: Self-employment (full)
Turnover over 90,000, or you need capital allowances, adjustments or averaging.
The official form on GOV.UKSA104S: Partnership
You share the business with someone else. Your share of the profit goes here instead.
The official form on GOV.UKSA101: Additional information
Savings, investment reliefs and pension charges. This is the UK equivalent of a Schedule 1.
The official form on GOV.UKSA100: The main return
Every return needs it. Your self-employment figures feed straight into it.
The official form on GOV.UKThree things sole traders leave on the table
- Working from home. A flat rate by hours worked, or a share of your real bills if that comes to more.
- Pension contributions. They cut the profit you are taxed on and, above the higher rate threshold, save 40p in the pound.
- Trading losses. An early loss can often be set against wages from the same year or carried back.