Self Assessment 2025/26: your checklist before 31 January 2027

The online return for the 2025/26 tax year, and any tax owed, is due by 31 January 2027.

Use this checklist to get organised early and avoid penalties.

Who needs to file

  • Self-employed people with income over £1,000
  • Landlords with rental income
  • Company directors with untaxed income such as dividends
  • Anyone with foreign income or gains
  • People who owe the High Income Child Benefit Charge and do not pay it through their tax code
  • Anyone HMRC has asked to file

Key dates

  • 5 October 2026: deadline to register if you are new to Self Assessment
  • 31 October 2026: paper return deadline
  • 30 December 2026: file online by this date if you want tax under £3,000 collected through your tax code
  • 31 January 2027: online return, balancing payment and first payment on account
  • 31 July 2027: second payment on account

What to gather

  • Your UTR and Government Gateway login
  • P60, P45 or P11D if you were employed
  • Business income and expenses, or your Xero records
  • Rental income and costs, including mortgage interest
  • Bank and savings interest, dividends and pension contributions
  • Details of any foreign income and tax paid abroad
  • Gift Aid donations

Payments on account

If your last bill was over £1,000 and less than 80% of your tax was collected at source, HMRC asks for two advance payments towards next year, each half of this year's bill. If your income has fallen, you can apply to reduce them.

Penalties if you are late

A late return costs £100 straight away, then £10 a day after three months up to £900, then further penalties after six and twelve months. Late payment adds 5% at 30 days, six months and twelve months, plus interest.

Common questions

Can I still register if I have missed 5 October?

Yes. Register as soon as possible. If you file and pay by 31 January you can usually avoid a penalty for registering late.

What if I cannot pay in full?

You may be able to set up a Time to Pay arrangement with HMRC. Contact them before the deadline.

Do I need to file if my only income is a salary?

Usually not. Since 2023/24 a high salary taxed through PAYE no longer means you must file on its own. You may still need to if you have other untaxed income or HMRC asks you to.

How early should I send my records?

The sooner the better. Sending them in the autumn means you know your bill well before January.

Let's talk

Every client is different, so there is no standard fee. Tell us a little about your situation and we'll come back with a personalised quote, usually within one working day.