HM Revenue & Customs (HMRC) is chasing people who have failed to submit their self-assessment tax returns for 2009-10 or earlier.
HMRC does not know how many people are involved, partly because it wants people to come forward voluntarily, but have kept quiet. Examples are people who started earning investment or rental income. Those who pay by 2 October 2012 may avoid the normal penalty of up to 100% of the tax owed.
"By taking part in the campaign, people will receive the best terms on offer and HMRC expects that most will not have to pay this penalty," HMRC said.
However, they will still have to pay:
• any tax owed
• the accumulated interest on it
• the fixed penalties for the late submission of self-assessment returns, and
• the surcharges for the late payment of the tax owed, if they are already within the self-assessment system.