What's the difference between using your credit card and Joe Hockey's first budget?

Thursday is the last time a signature can be used when flashing the plastic, whereas there is nothing so definite about the signing off of the budget.

Credit and debit cardholders will have to use their four-digit Personal Identification Number (PIN) when making in-store purchases from Friday in an attempt to clamp down on hundreds of millions of dollars worth of card fraud each year.

The government probably wishes getting the budget through a hostile Senate was as simple as punching in a few numbers.

But Prime Minister Tony Abbott has no intention of calling for a double dissolution election or holding a mini-budget as demanded by the leader of the Palmer United Party, Clive Palmer, who says the government's budget strategy has failed.

Mr Abbott says Senate crossbenchers need to respect the coalition's mandate to get the budget back under control.

"We cannot continue spending money that we just don't have," he told Fairfax radio on Thursday.

Mr Hockey has been in talks with a number of crossbenchers in recent days.

But Opposition Leader Bill Shorten said everyone except the prime minister and treasurer believes this is a "grotesquely unpopular" budget.

While he believes in sensible reforms, he said there was no case to engage in "incredibly difficult cuts".

It's not just opposition parties expressing concerns.

The outgoing boss of National Australia Bank, Cameron Clyde, has lashed the prime minister's planned paid parental leave scheme, saying the country cannot afford it.

The scheme, to be funded by a 1.5 per cent levy on Australia's top 3000 companies, would cost NAB $100 million.

Yet Mr Clyde said feedback from the bank's workforce indicated child care was the biggest barrier to women re-entering the workforce, not paid leave when having a baby.

"If I could spend that $100 million on child care as opposed to a paid parental leave scheme, that would be far more productive," he told Fairfax radio.

But prime minister is committed to the scheme.

"I don't break promises and this was a promise I took to two elections," Mr Abbott said.