Written by the TaxTune Editorial Team · Reviewed by our qualified accountants · Updated for 2026
The quick answer For your first Self Assessment, register with HMRC by 5 October, wait for your UTR and activation code by post, gather your income and expense records, file online by 31 January, and pay any tax by the same date. Starting early is the single best thing you can do.

Your first return, step by step

  1. Register by 5 October. Register for Self Assessment after your first tax year of self employment or untaxed income.
  2. Get your UTR and activate. HMRC posts your UTR within about 10 working days, then an activation code for your online account.
  3. Gather your records. Income, expenses with receipts, and any P60, interest or dividend details.
  4. Fill in the return. Tick the sections that apply, enter your figures, and let HMRC calculate the tax.
  5. File and pay by 31 January. Submit online, save the receipt, and pay the bill, plus any first payment on account.

What surprises first timers

Two things catch people out. The registration and activation come by post, so leaving it to January is risky. And if your bill is over £1,000, payments on account can make the first January feel like paying one and a half times the tax. Knowing both in advance keeps it calm.

First return feeling overwhelming?

You do not have to work it out alone. TaxTune registers you, tells you exactly what to gather, prepares and files the return, and makes your first year simple.

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Frequently asked questions

How do I do Self Assessment for the first time?

Register with HMRC by 5 October, get your UTR and activation code by post, gather your records, file online by 31 January and pay any tax by the same date.

How early should I start my first return?

As early as possible. Registration and the activation code come by post and take a couple of weeks, so leaving it to January risks missing the deadline.

What records do I need for my first return?

Your income, business expenses with receipts, and details of any employment, savings interest or dividends. Good records make the return quick and accurate.

What is a payment on account, and will I have one?

It is an advance instalment toward next year, due if your bill is over £1,000. It can make the first January feel larger, so it is worth knowing in advance.

Can an accountant help with a first return?

Yes, and many first timers use one to get set up correctly, claim everything, and avoid mistakes. We handle the whole thing on a fixed fee.