The Australian Taxation Office says the "robo-debt" debacle is not its fault and it is unhappy being publicly linked with Centrelink's controversial debt-recovery program.

Senior ATO officials told a Senate committee investigating robodebt on Wednesday that the ATO simply handed its data on taxpayers over to Centrelink's parent department, Human Services, which then used an automated system to raise debts.

It also emerged in Wednesday's hearings that Centrelink had been paid just $24 million of the $300 million it says it is owed under the program with some debtors paying back as little as $5 per week.

But Department of Human Services Secretary Kathryn Campbell said there were no plans to heed the widespread calls for the program to be scrapped and that it would continue with "refinements".