This year's Australian Budget imposed a 0.06 of a percentage point annual levy on the liabilities of the country's five biggest banks.

This would pull in about A$1.5 billion (NZ$1.6b), analysts said, or 5% of the combined group profits of the banks.

That has prompted warnings that consumers, including those in New Zealand, could see their banking costs increase. Goldman Sachs said banks would have to increase mortgage rates by 14 basis points to meet the cost.

But UBS said banks could offset it by reducing what they paid their third-party distributors.

It said brokers were paid more than A$2.4 billion in commissions in 2015, and their fees made up 23% of the cost of a major bank’s entire personal and consumer banking unit.

The analysts estimated that commissions added 16 basis points to every Australian mortgages.

“We believe these payments are an illustration of excesses built into the financial system following a 26-year economic boom,” they said in a note titled Are Mortgage Brokers Overpaid?.

“We believe advice for a commoditised, single product such as a mortgage can be easily provided by roboadvice. The current quantum of economic rent being extracted by the mortgage broking industry is unrealistic and is likely to fall dramatically in coming years.

The analysts said they expected the banks to begin negotiating materially lower commission rates from the mortgage brokers on a fee-for-service basis.

But Mortgage and Finance Association of Australia chief executive Mike Felton said the $4600 figure had been determined by dividing the total amount of broker commissions in 2015 by just the number of loans written that year – not taking into account commission being paid on older loans.

“This has given them a commission per mortgage that is about double what it actually is in the year of acquisition," Felton said.