HMRC SA103F: self-employment full pages and expense boxes

If you are a sole trader in the UK, your Self Assessment return comes with a supplementary page for your business. Larger or more complex businesses use the SA103F, "Self-employment (full)". Its expense section is where most of your receipts end up, so it helps to know which box each one belongs in long before the 31 January deadline.

What the SA103F is

The SA103F is a supplementary page HMRC publishes for the SA100 Self Assessment tax return. It is for people who are self-employed and whose turnover was above the VAT threshold, or whose tax affairs are more complex (GOV.UK SA103F page, as of October 2026). It covers business details, income, a full breakdown of expenses, capital allowances, adjustments to arrive at taxable profit, losses and Class 4 National Insurance.

For the online return of the 2025–26 tax year, the deadline is 31 January 2027; a paper return is due by 31 October 2026 (GOV.UK deadlines, as of October 2026).

SA103F or SA103S?

HMRC's notes for 2025–26 say to fill in the full pages if any of these apply (SA103F notes 2026, as of October 2026):

• your turnover was £90,000 or more (or would have been over a full year of trading)
• your accounting period ended before 31 March 2026, was not 12 months long, or did not end in the tax year
• you have adjustment income because you changed your accounting basis
• you need to adjust profits chargeable to Class 4 NICs
• you were in the Managing Serious Defaulters (MSD) programme

If none of them applies, you use the short pages (SA103S) instead.

The expense boxes

On the 2025–26 form, allowable expenses go in boxes 17 to 30, with the total in box 31. Next to each line is a "disallowable" box (32 to 45, total in box 46) for any private or non-deductible part included in the left-hand figure (SA103F 2026 form, as of October 2026).

If your annual turnover was below £90,000, the form lets you put only your total expenses in box 31 (unless you are in the MSD programme).

Points from the notes that often trip people up:

• Entertaining is not an allowable expense. If client entertainment is in box 24, the same amount also goes in box 39.
• Boxes 27 and 29 are only for traditional accounting, not the cash basis. Depreciation is not an allowable expense, so anything entered in box 29 also goes in box 44.
• Box 20 has exceptions: taxi and minicab drivers and road hauliers put fuel in box 17.
• Do not send receipts with the return. Keep them as records in case HMRC asks.

Making Tax Digital for Income Tax

Making Tax Digital (MTD) for Income Tax brings digital records, quarterly updates and a return sent from compatible software. Whether it applies depends on your qualifying income: your self-employment and property income before expenses. According to GOV.UK (eligibility guidance, as of October 2026):

• over £50,000 in the 2024–25 tax year: MTD from 6 April 2026
• over £30,000 in 2025–26: from 6 April 2027
• over £20,000 in 2026–27: from 6 April 2028

Quarterly updates are summaries with totals per income and expense category; HMRC does not receive individual receipts in them. With the standard periods, the deadlines are 7 August, 7 November, 7 February and 7 May (GOV.UK quarterly updates, as of October 2026). So the sorting work behind the expense boxes moves from once a year to every quarter.

How Bonro prepares the data

Bonro sorts each UK receipt into a category that follows the SA103F expense lines: box 17 and boxes 19 to 30. There is no category for construction-industry subcontractor payments (box 18). The summary CSV lists every receipt with its SA103F category, net amount, VAT and gross amount, so totals per box are a simple sum. The Xero CSV and QuickBooks CSV bring the same receipts into those programs. Every field can be checked and corrected before you export.

Bonro does not submit anything to HMRC, is not MTD software and does not send quarterly updates. You or your accountant use the files to prepare the return. The UK exports are part of the Pro plan; see Bonro's pricing for details.