Self-assessment tax deadline: Register by 5 October or face penalty

The deadline applies to the newly self-employed or those who had additional income in the last tax year

If you are newly self-employed or had additional income in the last tax year, 2014-15, you must register for self-assessment by Monday 5 October.

"Failure to register on time can result in penalties of up to 30 per cent of the tax due, or more in some cases, unless you pay the tax by 31 January," warns Tina Riches, national tax partner at the accountancy firm Smith & Williamson.

"While the tax authorities waived a number penalties for late tax returns in 2015, it should not be relied upon to do the same in 2016.

"There are a number of deadlines and charges associated with your tax return, so it is important to remain aware of them to avoid being fined."

Once you have registered for self-assessment, HM Revenue & Customs will give you a unique tax reference (UTR) and issue you with a tax return. That will be due by 31 January if you file online, or 31 October for those who use paper forms – or within three months from the issue of the return notice, if later. The UTR number is then used to track your return and eventual tax payment. You can register online at gov.uk/register-for-self-assessment.