Self-assessment tax return – rules and deadlines

A self-assessment tax return must be completed by the self-employed and others with more complicated tax affairs – for example, if you're a company director or a trustee.

Do I need to complete a self-assessment tax return?

If income tax contributions are taken automatically from you along with National Insurance contributions through pay as you earn (PAYE), and you don't have additional income on top, you probably don’t have to complete a self-assessment tax return.

In most cases, you only need to fill in a self-assessment tax return if you are:

  • Self-employed
  • A sole trader
  • A company director or a partner in a business partnership
  • A minister of religion (all faiths)
  • A member or name of Lloyds of London insurance market

and if any of the following conditions apply:

  • Your income is above £100,000
  • You have income from overseas that is taxed under UK law
  • You need to pay Capital Gains Tax after selling assets such as shares
  • Your income from property is more than £10,000 before expenses
  • Your income from savings or investments is more than £10,000, or income from untaxed savings is £2,500 or more

High income Child Benefit charge

If either you or your partner are eligible to receive Child Benefit and either of you have an income over £50,000, you will be liable for a tax charge under new rules. The new rules mean that those earning £50,000 or more will be entitled to progressively less child benefit as their income increases, with those earning more than £60,000 entitled to none at all.

Rather than calculate individual payments, the government pays everyone the full amount and 'claws back' overpayments in the form of a tax charge. If you're affected by the changes, you have two options:

  1. Opt out of receiving child benefit by either filling in the HMRC online form or contacting the Child Benefit Office by phone or post; or,
  2. Carry on receiving child benefit and pay the tax charge by filling in a self-assessment at the end of the year.

Declaring child benefit payments and filling in the self-assessment is the responsibility of the person earning £50,000 or more – if you both earn over this amount then it falls to the person who earns the most.

Important deadlines for self-assessment tax returns

If you need to fill in a self-assessment tax return, you should have these dates in your diary:

  • 5 October: the deadline to register for self-assessment with HMRC
  • 31 October: the deadline for returning your self-assessment tax return by post
  • 31 January: the deadline for filling in your self-assessment online and paying any tax you owe

Failure to meet these deadlines can result in an automatic £100 fine.

Remember that the tax year runs from April to April; so if you need to pay tax for the 2015/16 tax year, you'll need to register by 5 October 2016 and pay by 31 January 2017.

For advice on making the most out of your money when it comes to taxes, speak to a financial adviser.

The Financial Conduct Authority does not regulate taxation and trust advice.

Last updated: 05 April 2016