That's what we'll be asked to believe when the budget update is published next week. We'll be told Prime Minister Tony Abbott's new health package will save $3.5 billion whereas his old package would have saved $3.6 billion.

Part of the trick is that it isn't the co-payment that saves the government money, it's the cut to the Medicare rebate. That cut was always going to be $5 per consultation. If doctors had had the ability to charge a $7 co-payment they would have got an extra $2 in their pockets. Now they won't.

Another part of the trick is that the government will now cut some rebates by much more. Standard so-called Level B consultations of up to 10 minutes currently attract a $37.05 rebate. Under the changes they will classified as Level A and attract $16.95 for the young and concession holders and $11.95 everyone else.

And the two-year freeze on Medicare rebates that was going to extend to June 2016 will now become a four-year freeze, extending to June 2018.

Doctors will lose just as much as before, but in different ways and for longer.

At least that's what the budget update will say.

All of the changes but one will be introduced through the back door by regulation rather than by legislation, which requires the approval of Parliament. But regulations can be disallowed by the Parliament after they are introduced. Just last month the Senate disallowed the regulations that purported to water down consumer protection under financial advice law.

There's every reason to think its prepared to do it again if it doesn't like co-payments, meaning that while the $3.5 billion saving will be in the budget update, most of it will never be banked.

Peter Martin is economics editor of The Age.