The first self-assessment ambushes every freelancer the same way: not the form, but the timing of the payments. Learn the calendar and the rest is bookkeeping.
The Calendar That Matters
- 5 October: deadline to register for self-assessment after your first self-employed tax year
- 31 January: online return deadline AND payment of everything owed for the year ended the previous April
- 31 January + 31 July: payments on account — advance instalments for the current year, each 50% of last year’s bill
Payments on Account: The Famous Ambush
Your first January bill is often 150% of a year’s tax: the full year owed, plus the first advance instalment. A freelancer owing £4,000 pays £6,000 that January and £2,000 in July. Nobody warns them; now you are warned. The fix: save as you earn — 25–30% of profit into a separate account, untouchable.
Expenses Worth Claiming
Anything wholly and exclusively for business: software, equipment, professional insurance and subscriptions, accountancy, travel (not commuting), phone/broadband business proportion, and either simplified working-from-home flat rates or a calculated share of household bills. Under £1,000 of income? The trading allowance may beat itemising entirely.
Keep It Boring
Separate bank account, receipts photographed as they happen, a spreadsheet updated monthly. Making Tax Digital is progressively pulling sole traders into quarterly digital reporting — clean habits now are the whole preparation.