Treasurer Joe Hockey has conceded the $7 Medicare co-payment introduced in the budget amounts to a new tax - but denied the Abbott government had lied to Australians that it would not introduce any new taxes.

Appearing on ABC's Q&A program, Mr Hockey was jeered early on by the audience in Penrith in Sydney's western suburbs until host Tony Jones asked for respect for the Treasurer.

"We didn't say we wouldn't raise any taxes. That's absurd because we went to the last election promising to introduce a levy for the paid parental leave scheme," Mr Hockey said.