THE federal Coalition's economic credibility has been dealt a blow after a tribunal found that two accountants who costed its 2010 election policies had breached professional standards.

The ruling is an embarrassment to shadow treasurer Joe Hockey, who wrongly insisted during the campaign that the accountants' policy costings had been audited.

Shadow Treasurer Joe Hockey. Credit:Alex Ellinghausen

Geoffrey Phillip Kid and Cyrus Patell, of the Perth office of accountants WHK Horwath, produced a one-page report for the Coalition on its policies two days before the election.

Mr Hockey said at the time that the pair had certified "in law that our numbers are accurate''.