Date: 18 January 2012

If you're self-employed or have other income that isn't taxed directly through your pay, you normally have to send in your tax return to HM Revenue and Customs (HMRC) every year.

HMRC has introduced new penalties if you send in your self-assessment tax return late online. You must send in your return by 31 January, otherwise the penalties are as follows:

• £100 penalty on 1 February, plus
• £10 a day penalty from 1 May for 90 days - a maximum of £900, if the return is still not submitted, plus
• £300 fine on 1 August if the return is still not submitted, or 5% of the tax due if that is more, plus
• £300 penalty on 1 February the following year if the return is still not submitted, or 5% of the tax due if that is more.

It used to be that the maximum penalty you could face couldn't be more than the amount of tax you owe to HMRC, but this isn't the case anymore. You could end up paying up to £1,600 in penalties even if you don't owe anything to HMRC or they owe you a refund.

This is why it's really important you get your return in on time. If you've got any problems completing your tax return, get help as soon as possible. If you sent in a paper tax return, the deadline was 31 October last year, and the penalties would start to build up from then, the same as for online returns.

Because some HMRC staff are due to take strike action on 31 January, HMRC have decided that people filing their tax returns online will not be penalised if they do not get the return in by 31 January, provided it is received by midnight on 2 February. This allows customers who have a query about their tax return to speak to an adviser before the online filing deadline. More information is on the HMRC website at www.hmrc.gov.uk.

For more information on who can help, see Help with tax problems. For information on tax returns and who has to do them, see Tax returns.