HMRC Expense Categories SA103 2026

The problem: most freelancers categorise expenses wrong

2.9 million UK freelancers need to categorise expenses for Self Assessment. Most get it wrong, and the mistakes cost them money in both directions. Over-claiming gets flagged by HMRC. Under-claiming means paying more tax than you owe.

• Claiming client meals (not deductible for sole traders under HMRC rules)
• Missing home office simplified expenses (£10-£26/month depending on hours)
• Treating capital items like a new laptop as a revenue expense in the wrong box
• Not knowing which mileage rate applies (45p for first 10,000 miles, 25p after)
• MTD means quarterly categorisation, shoebox approach no longer works

What this tool categorises

• Every expense mapped to the correct SA103 box with HMRC box number
• Capital vs revenue distinction, flags items that go under Capital Allowances
• Mileage tracking at 45p/25p split across the tax year
• Home office allowance, simplified method or actual cost method
• VAT summaries for VAT-registered businesses
• MTD quarterly position, running profit and loss by quarter
• Deductibility checks: "Is X deductible?" answered instantly with the relevant HMRC category

SA103 box coverage

The tool covers every category on the Self Assessment SA103 short and full forms: cost of goods sold (Box 17), car and travel (Box 20), wages and staff costs (Box 21), premises costs (Box 23), repairs and maintenance (Box 25), professional fees (Box 26), bank charges (Box 27), phone and office costs (Box 28), advertising and marketing (Box 29), and other allowable expenses (Box 31).

Capital Allowances, including the Annual Investment Allowance, Writing Down Allowance, and First Year Allowances, are handled separately and flagged so they go on the correct supplementary pages.