Landlords who have failed to declare their property profits have one last chance to pay what they owe under Britain’s first tax amnesty.

HM Revenue & Customs is warning property investors that specialist task forces are ready to target those with undeclared rent profits or gains from disposing of homes.

At the same time as another task force aiming to uncover illicit property dealings started work in the South East, HMRC announced the general amnesty.

John Whiting, from the Chartered Institute of Taxation said: “This is about urging people to come in out of the cold and to join the rest of us who pay taxes on time and in full. This is about clamping down on the minority who don’t.”

HMRC promises to crack down on anyone who fails to file details on their full earnings with harsh financial penalties and even possible criminal prosecution.

After a similar amnesty for plumbers finished recently, five tradesmen were arrested, 600 faced tax investigations, and one was sent to prison after admitting not declaring any earnings and owing £50,000 in tax.

Taking part in the amnesty will still involve a penalty – paying at least any tax owed plus 3% interest.

“We may not forget every penalty, but will treat those who co-operate leniently,” said an HMRC spokesman.

“Innocent mistakes are unlikely to be punished, especially if the taxpayer asked for advice and received wrong information.”

Despite the amnesty, HMRC refuses to rule out stiffer penalties or prosecution for the worst offenders.

HMRC’s director-general of enforcement and compliance Jennie Grainger said: “The message is simple: the net is closing. We will find out if you are working off the books, if you haven’t disclosed investment income, or if you have assets offshore. Do not believe HMRC won’t take action – it is only a matter of time before we catch up with you.”