Two major banks have announced changes to their repayment requirements.

The Commonwealth Bank (CBA) is dropping about 750,000 customers' home loan repayments to the minimum amount.

Customers must opt out if they wish to continue to make repayments over the minimum amount.

The National Australia Bank (NAB) has reduced its minimum repayment levels for credit cards down to 0.5 per cent of a customer's closing balance or just $5 — whichever is greater.

The changes are presented as measures to help customers, but they could see many paying far more interest and being locked in for longer.

“Some people are going to miss that [CBA] email … they might just dismiss it as another piece of marketing from a bank, and they won't know what's happened until it's too late,” Financial Counselling Australia chief executive Fiona Guthrie said.

“By the time they do find out, which could be couple of weeks, a couple of months or even later, it means that you'll end up paying more and the loan will take longer to pay off.

“It can be substantial, it could be tens of thousands of dollars for some people.

“Some of the messaging that we're hearing at the moment is; ‘Defer, don't worry about it’.

“It [the debt] will come back. Those debts don't go away. Your bank loans, your personal loans, loans with finance companies with credit cards — pay what you can afford, make the best decision for yourself in the longer term.”

Ms Guthrie said the banks should offer a broader range of approaches.

“I don't actually want to be critical of the Commonwealth Bank or the banking industry because they're doing a lot of really good things here, and they're trying to be helpful,” she said.

“[But] this may not have been the right decision.

“Your house of course is your biggest asset and it's often really sensible, if you can afford to pay more than minimum repayments, to do that.”