A practical walkthrough of filing your UK Self Assessment return online.
Register with HMRC for Self Assessment by 5 October following the end of the tax year. You'll receive a Unique Taxpayer Reference (UTR) and need to set up your online Government Gateway account.
Log in via Government Gateway, select the relevant tax year, and work through the sections relevant to your income types (employment, self-employment, property, dividends, capital gains, etc).
HMRC's system calculates your tax due automatically based on what you've entered. Review it against your own estimate — see our Self-Assessment Tax Calculator.
Online returns are due by 31 January following the end of the tax year. Submitting early doesn't mean paying early — your payment is still due by the same date, but it gives you more time to budget for it.
Pay via the HMRC online service, bank transfer, or other accepted methods by 31 January. If your bill is over £1,000, you may also need to make Payments on Account toward the following year.
Check your key filing dates for this year.
See the Filing Calendar →This is a general walkthrough, not a substitute for HMRC's own guidance. For complex situations, consider consulting an accountant.