Millions of people have just ten days to act, or risk a £100 fine of HMRC which could later become a considerably higher sum.
The government department said around 5.7 million people are due to file a tax return by January 31. Anyone who doesn't do so by this time risks being hit with a £100 penalty, even if they don't owe any tax.
Myrtle Lloyd, HMRC’s Director General for Customer Services, said: "My message to those yet to start is: don’t delay, do it online. HMRC provides lots of useful information to help you get started. Visit GOV.UK and search ‘Self Assessment’."
