Self Assessment Tax Return 2026/27: The Honest Guide

For most filers, Self Assessment is a half-day job, not a month-long ordeal. The "it is hard" narrative is HMRC accidental marketing.

You only need to file if you cross specific triggers: side income over £1,000, rental income over £1,000, dividends or interest beyond the allowances, CGT above £3,000, or total income over £150,000.

Four mistakes cause most HMRC enquiries: round-number estimates, missing untaxed bank interest, forgetting dividends or crypto, and claiming personal expenses as business costs.

Pay an accountant once income passes £100,000, or when you combine self-employment with rental income and dividends. Below that, doing it yourself is the rational call.