THOUSANDS of Australians are stuck in a “mortgage prison” with new lending criteria leaving them unable to refinance their loans to get a better rate.

Changes in bank rules around living expenses calculations have effectively wiped huge amounts off the maximum a bank will allow you to borrow.

Many people are now finding they originally borrowed more than a bank would lend them under current conditions, meaning they haven’t got the option of shopping around to get a better interest rate — no bank will lend them the amount they need.

Lending criteria has been tightened in the past year. The ongoing Financial Services Royal Commission is likely to tighten the criteria even further — meaning people will be able to borrow even less than they once did.

With homeowners unable to shop around, they can be stuck paying a high interest rate, which will leave them potentially paying tens of thousands, even hundreds of thousands more over the life of a loan.

Recently the Bank of Queensland and Auswide Bank announced they will raise variable mortgage rates as their borrowing costs grow. This follows a warning last month from Credit Suisse that out-of-cycle rate rises were on the table.

Precise numbers of Australia’s mortgage prisoners are hard to come by, but Mozo investment and lending expert Steve Jovcevski told news.com.au that he expected most of them are those who have borrowed and bought in the last five years.

He said the changes in how mortgage eligibility are calculated have made a huge difference for many recent borrowers, particularly as banks start to raise rates.

Before lending criteria was changed, a flat rate for living expenses was applied, resulting in many hopeful homebuyers borrowing much more than they now could.

Mr Jovcevski gave an example of a couple earning $120,000 between them, who bought a home in 2013, borrowing a total of $800,000 at 5% per annum, and who would be paying $4295 a month on their loan, leaving $3680 for monthly expenses.

Even with a pay raise between them bringing their income up to $129,000 the couple now faces a change in rules around living expenses that raises the bar for any borrower.

Previously banks estimated these expenses, with a buffer of 1.5 per cent to safeguard against rate rises. Now they are looking closer at people’s monthly expenditure, and have increased the buffer to 2 per cent.

Under this new criteria, the couple would only be able to borrow $680,000, even though their income hasn’t changed.

And because their mortgage is still more than $680,000, they won’t be able to find another bank to make up the difference — meaning they’re stuck with their original loan paying a high interest rate.

The difference between a 5 per cent home loan and a 3.8 per cent home loan amounts to $149,272 over the life of the loan.

“When a customer is essentially tied to a provider, they are at the mercy of whatever rate rise or conditions the bank chooses to impose. Given the current situation, banks have the power to hold some of their customers prisoners,” Mr Jovcevski said.

“The sad reality is borrowers who need competitive mortgage rates to stay financially afloat are most likely to be mortgage prisoners.”

First Home Buyers Australia director Taj Singh said he was very much aware of the crackdown on borrowing limits and living expenses for borrowers.

The mortgage broker said this was putting many borrowers in a position where they can no longer refinance to get a better rate.

He said given many loans were refinanced every four to six years, this issue would continue to be felt for recent first home buyers.

But Grattan Institute fellow Brendan Coates told news.com.au that the impact of any tighter lending conditions would be largely confined to a small section of borrowers as rising house prices had given borrowing room to homeowners who had been in the market for several years.

He predicted the impact would largely be felt in those who’d borrowed more than 90 per cent of the value of their house, a number which had fallen in recent years from 14 per cent in 2014 to 7 per cent in 2018.

But he did say that if house prices in Sydney and Melbourne continue their fall then the pain could spread to more borrowers.