It is well publicised that the filing date for self-assessment tax returns was midnight on January 31.

What is not so well publicised is that for those who were filing their own tax returns at the last minute and discovered they had lost their User ID or PIN, or had not yet applied for one, their deadline is extended to 15 February.

In response to requests for a new User ID or PIN between midnight on 21 January and midnight on 31 January, HMRC sent out automated emails saying “file your tax return online before midnight on February 15 to avoid receiving a penalty.” So for those who missed the January 31 deadline due to an inability to submit the return online, there is no penalty if you file it by midnight on February 15, although the return is still technically late.

Many people who are affected by the new higher income charge on child benefit have not yet registered for self-assessment. So their 2012/13 tax return is late and there is already an automatic £100 penalty. What many people are unaware of is how quickly the penalties can mount up if the return remains outstanding for six months. After a return is three months late, HMRC can issue daily penalties of £10 a day for the next 90 days, totalling £900.

Once the return is six months late, even if there is no tax due, the total penalty faced is £1,300. I would advise anyone who thinks they should have filed a tax return for 2012/13 to take action now to avoid further penalties. Burying your head in the sand in this situation will only make things worse as the penalties rack up so quickly.