You must complete a self-assessment income tax return if you are in business, either as a self-employed person or as a company director. Simple planning and the right advice can make completing your income tax return relatively painless.
Self-assessment tax return timescales
You need to file your income tax return online by 31 January following the end of the tax year (5 April). If you want to file a paper income tax return instead, there is an earlier 31 October deadline. Your self-assessment tax return planning needs to work towards these deadlines. Failure to file your return and pay any resulting tax due on time will result in penalty charges.
If you need to complete a self-assessment tax return, you may be notified automatically by HM Revenue & Customs (HMRC). If you aren’t, it’s up to you to let them know that you need to file a return. If you were self-employed during the previous tax year and HMRC doesn’t already know, you must register by 5 October at the latest.
You can complete your income tax return yourself or ask your accountant to do it. If you are doing your own self-assessment tax return, you will probably want to do it online. You will need to register for HMRC online services. Bear in mind that it can take about a week to activate online access, so leave enough time.
If you are using a paper self-assessment tax return, you should also allow time for any postal delays — either in receiving the forms or delivery of the completed income tax return to HMRC. You will also need to check that you have got all the pages that you need to complete, and if necessary ask for additional supplementary self-assessment tax return pages to suit your circumstances.
Self-assessment tax return records
Completing your self-assessment tax return can be relatively straightforward, provided that you have well-organised tax records. These need to include details of any employment income and other types of personal income, such as savings income or capital gains from selling investments. You also need details of any reliefs you will be claiming on your income tax return such as for pension contributions or gifts to charity.
If you are self-employed, you’ll need your business tax records. If you run your business as a company, the company will need to complete a separate corporation tax return. If you are in a partnership, you’ll need to include details of your share of the partnership income on your self-assessment tax return, but the partnership also needs to file a partnership tax return.