A system error is being blamed for incorrect childcare benefit payments being deposited into Australian bank accounts.
The Department of Human Services is reviewing about 8,000 payments made over a two-day period around Easter after it emerged some people had been overpaid thousands of dollars.
The money, if incorrectly deposited, will need to be repaid in full.
DHS general manager Hank Jongen said most of the payments were between $50 and $2,000, but admitted some were as high as $10,000.
Mr Jongen said he did not know how many of the 8,000 payments were made in error.
"As a result of a system upgrade, there were unintended consequences which resulted in the system not identifying one income of two-income families," he told ABC Radio Melbourne.
"It assessed some people being eligible for arrears and it generated automated top-up payments.
"We nipped it in the bud to ensure no more people were affected and we're currently working through the cases."
Mr Jongen provided assurances that repayment plans would be flexible in cases where large sums of the money had been spent.
"We recognise that we've caused this inconvenience and we apologise," he said.
'I don't deserve this $10,000'
Shane Scanlon contacted ABC Melbourne when he and his partner noticed an extra $10,000 in their account.
He said he contacted the department but his attempt to return the money had been thwarted.
"They've basically said they can't tell us where it's come from, why it's there. [They said] be careful on spending it, just in case.
"They can't tell you whether you're entitled to it or not — I don't deserve this $10,000."
It comes after recent figures showed Centrelink had reduced, waived or wrote off more than 77,500 so-called robo-debts.
The automated debt collection system has come under fire for wrongly issued notices being sent to people.
Previously, debt collection notices were sent after a Centrelink officer completed a manual investigation.
