When your first Self Assessment return and payment are due

Katerina Galkina · EN · 07/10/2026

Identify the correct tax year first

The UK tax year runs from 6 April to 5 April. Starting work during a calendar year does not make your first return a January-to-December return. Record the business start date and organise receipts and expenses for the relevant tax year.

Check whether you need a return through the Self Assessment guidance ↗. Registering, receiving a UTR, filing and paying are separate steps. Telling an employer or opening a business account does not notify HMRC for this purpose.

Separate the three deadlines

For 2025/26, ending on 5 April 2026, HMRC’s deadlines ↗ normally require notification by 5 October 2026, a paper return by 31 October 2026, or an online return and payment by 31 January 2027. Check the specific dates for any other tax year.

If notification is late, register promptly and read HMRC’s individual instructions. A special filing deadline after late registration does not necessarily postpone payment. Do not leave account access until the last week of January: setting up access and verifying your identity can take time.

Prepare records and a payment reserve

Gather your UTR, National Insurance number, income and expense records, statements, employment information and other reportable income. Distinguish turnover from profit. Income already taxed through PAYE may still be needed for the overall calculation.

Registering for Self Assessment ↗ does not require immediate payment of the entire estimated annual liability. Nevertheless, estimate the future bill and set money aside. If using an accountant, agree a document-delivery date well before the filing deadline. Appointing a professional does not remove your responsibility for the return.

Check the first bill and submission

Your first substantial January payment can include tax for the completed year and a first payment on account for the next year. The deadline guidance ↗ also identifies 31 July as the second payment-on-account date. Do not budget solely for one year’s final tax liability.

After filing, save the submission receipt and check that the return is actually submitted, rather than saved as a draft. Separately confirm that payment reached the correct tax account with the right reference. If you cannot pay everything, contact HMRC before the deadline. Difficulty paying is not a reason to omit filing the return.