What happens if Centrelink accidentally credits too much money to my income management account?

In Plain English:

If Centrelink pays you too much family assistance, one-off payments to families, payments under section 67EB, payments under section 205A or 205C, economic security strategy payment to families, back to school bonus, single income family bonus, a clean energy advance, ETR payment, 2020 economic support payment, additional economic support payment 2020 or additional economic support payment 2021, the overpaid amount becomes a debt you owe to the government.

Detailed Explanation:

According to section 70 of the A New Tax System (Family Assistance) (Administration) Act 1999:

If an amount has been paid by way of family assistance, one-off payment to families, a payment under section 67EB, a payment under section 205A or 205C, economic security strategy payment to families, back to school bonus, single income family bonus, a clean energy advance, ETR payment, 2020 economic support payment, additional economic support payment 2020 or additional economic support payment 2021, the amount is a debt due to the Commonwealth only to the extent to which a provision of: (a) this Act; or (b) the Data-matching Program (Assistance and Tax) Act 1990; expressly provides that it is.

This means that if you receive an overpayment of these benefits, it is considered a debt owed to the Commonwealth, and Centrelink is entitled to recover the overpayment from you.