By Alice Uribe

SYDNEY--Australia has yet to map out what support will be available for businesses and households beyond September when current stimulus programs are due to end, with many industries facing sharply differing outlooks.

The easing of restrictions across Australia has enabled shops to reopen, restaurants to allow sit-down dining, and live sports matches to be shown on television again. But for many of the hardest-hit sectors, including aviation and arts and entertainment, the pace of recovery is slow if it's happening at all.

That's fuelling concern among investors in Australian banks that bad debts will rise once the government's JobKeeper wage subsidy and six-month loan deferrals end.

Ross McEwan, chief executive of National Australia Bank Ltd., said the government could craft support programs targeting specific industries, citing tourism as one example.

"I do think there's a path to look after industries that have been very badly damaged that will take a lot longer," Mr. McEwan said at a Bloomberg-hosted conference. "I would expect to see some of those industries with some form of support for a long period of time."

That appears to dovetail with the government's thinking. On Tuesday, Prime Minister Scott Morrison signaled the government would announce help for the creative and entertainment industries next month, given they have been left out of the early recovery phase due to social-distancing rules.

"We understand that different sectors and different parts of the country are going to be impacted far worse than others," Mr. Morrison said.

Australia's banks face challenges on two fronts. Workers who have been furloughed or lost their job due to the pandemic may struggle to repay home loans if there is no assistance beyond September. Many businesses risk defaulting on their loans if the recovery doesn't accelerate.

Lenders have begun conducting three-month check-ins with customers who have deferred loans as part of an agreement with the prudential regulator. Those meetings will help them to gauge ongoing financial-stress levels, they say.

Citi said its initial assumptions suggest that 20% of deferred customers may default. Another 30% may need further extensions, but with a view to being able to reestablish payments in time, it estimates.

Commonwealth Bank of Australia said 15-20% of customers who requested pauses to their loan repayments have been continuing to make some sort of payment, with some exiting the deferral early. Of the 127,00 customers whose mortgage deferral request was approved, 15,000 decided not to take it up.

"We are starting to talk about what customers are going to do, obviously restarting payments being the best of that," a CBA spokesperson said. "We want to come up with a solution that is right for each customer, not a blanket solution that might not be the right answer for a group of people."

NAB's Mr. McEwan said the bank's balance sheet was his top concern, assuming that good businesses will survive and struggling businesses will not.

"I've been very careful: Don't support customers that won't be able to pay back, because it's not in their interests or our own," he said.

Citi analysts said regulators may be worried about a possible 'cliff' on the horizon. "Based on anecdotal feedback from industry participants, it is indicating that the regulators could be now exploring the possibility of providing further capital relief to loan deferrals that need extending beyond six months," it said.

The Australian Prudential Regulation Authority currently allows banks not to treat the deferral period as arrears, but there is not certainty this will continue. Industry experts say bank capital could be at risk if deferral periods are extended without additional relief.

Citi said further capital relief for banks would help, but may need to be nuanced. "It has been suggested that loans that need further deferral would be characterized into four buckets, with three of the four eligible for further capital and provisioning relief in some form," it said.

APRA chairman Wayne Byres told a Senate Select Committee on Covid-19 last month that the banking industry was operating with a holding strategy and risks remained.

"We can't keep pretending that everything is in good shape if there are customers who are clearly not going to be able to repay their loans," he said. "But we don't want to put pressure on a large group of customers just at the wrong point in the cycle."

Based on analysis of Australian Banking Association data, Morgans says the total dollar value of home loans deferred was 176 billion Australian dollars (US$122 billion) at June 19, or around 10% of the current stock of bank-issued home loans.

"If 10% of home loan borrowers continue to remain in hardship come the end of September, then we do not expect the banks to start foreclosing on 1 in 10 borrowers," Morgans says. "Rather we expect the banks to extend loan repayment holidays."

It also thinks the government will extend support measures if the unemployment rate, currently at a 19-year high of 7.1%, stays elevated.

Write to Alice Uribe at alice.uribe@wsj.com