Bank fees can chew up as much as a 10th of the incomes of some Indigenous people living in remote areas, and banks are not actively promoting fee-free accounts to eligible customers, the royal commission heard on Tuesday.

Nathan Boyle, who works in the Australian Securities and Investments Commission's indigenous outreach program, told the royal commission in Darwin about the disproportionate impact of account-keeping fees, informal overdrafts, ATM fees, and dishonour fees on vulnerable consumers.

Mr Boyle said because many of the consumers in remote Indigenous communities had low incomes, a fee of $10 or $20 was a significant share of their income.

He gave the example of a customer being charged $20 a fortnight, which he said could be about 10 per cent of a low income earner's income.