It's been making headlines since summer, when thousands of Australians suddenly found out they owed money to Centrelink.
Critics call it "robodebt", but how does the controversial system actually work?
What is it?
The official name is the Online Compliance Intervention.
How does it work?
OK, so what's changed?
If these are just requests for more information, why are people getting debts?
How is that allowed?
How many of the debts are real?
How do miscalculations happen?
So are some people paying debts they don't think they owe?
That doesn't seem fair...
How many people are trying to prove they don't owe these debts?
Background Briefing filed a freedom of information request to find out how many people were asking for an online reassessment or a formal review of their debt.
It was blocked by the department, who said it would generate too much work for them to find out.
(That's after they said they'd found the documents, and after Background Briefing paid them $45 in search and retrieval fees.)
How much money has it recovered so far?
The department also refused to provide numbers on how much money had been paid back to date.
What happens next?