The Worldwide Disclosure Facility (WDF), which was announced in the 2015 Budget, will offer no special deals to those who come forward but will be the last chance for people to come clean before a new set of tougher penalties is introduced.
"HMRC is getting even tougher on tax evasion," said Jennie Granger, HMRC director general of enforcement and compliance. "We relentlessly pursue tax evaders to ensure they pay every penny of the taxes and fines they owe, pushing for the toughest possible sanctions where appropriate."
The taxman has also revealed today it will start factoring into its penalty calculations how long it has taken somebody to put their affairs in order, meaning those who have been dragging their feet for a while or have ignored opportunities in the past to disclose outstanding liabilities might receive little to no deduction for voluntary disclosure.
The WDF launch date was mentioned last month, when HMRC proposed new laws which would slap those who do not come forward to cough up outstanding taxes from offshore investments and accounts with harsher penalties.
The new Requirement to Correct rules are being consulted on until mid-October.
HMRC is also shortly due to start receiving a slew of data on the offshore dealings of UK taxpayers as part of new data sharing arrangements.
HMRC has raked in over £2.4bn from offshore evasion initiatives since 2010.
What you need to know