Australians with offshore accounts in the Isle of Man are being sent letters to encourage them to disclose any tax they owe.

Australian Tax Commissioner Michael D’Ascenzo announced the initiative with this warning: 'We are increasing our audit activities in cases where people may try to conceal income and assets offshore in tax havens. Taxpayers who contact us before they are the subject of an audit and make a full and true disclosure will have reduced shortfall penalties. There is nothing wrong with holding an offshore account or investing overseas as long as you pay any Australian tax due.'

Letters are to be sent to people identified as having an offshore debit or credit card in Jersey, Guernsey or the Isle of Man, or identified through AUSTRAC data as having dealings with those jurisdictions.

D’Ascenzo (pictured) added: 'I urge people to review their tax returns and if they have undisclosed income to contact us before we contact them. Helping people do the right thing and taking a firm approach with those who don’t builds confidence in the tax system and helps create a level playing field for everyone.'