Centrelink says it will run about 500,000 robo-debt reviews each year, despite calls to scrap the program.

The Department of Human Services has plans for another 1.6 million automatic debt reviews over the next three years, even though its own data shows 60 per cent of people they target either refuse to talk to Centrelink or drop out part way through.

The robo-debt system has hit thousands of people with debts they do not owe, putting them through a complex review process, and taking money from tax returns without warning.

“The latest iteration of the online compliance system, which customers use to complete their reviews, is modern, easy to use, and transparent,” the department said in its submission to a Senate inquiry into the system.

“A review process does not commence without the person undertaking some action.

“Customers do not need to take legal action for an independent review of a decision to be undertaken.”

Several people have taken legal against their debt letters, while the Labor opposition has backed a class action.

The department has found that about 30 per cent of people do not engage with the review process at all, while another 30 per cent of people who start the process do not finish it.

“Where a person does not request a review of a debt decision, or engage with the department to provide more information, we have an obligation to pursue recovery of the debt and protect the integrity of the welfare system,” it said.

The most common cause for a Centrelink robo-debt letter is people reporting their net income instead of their gross income, or when job network providers fail to pass on accurate figures to Centrelink.

Media reports suggest DHS staff are required to hit a certain number of reviews each week, but the department denies this.

“Staff are coached regularly and will set aspirational targets for review finalisations in line with their individual learning and development needs,” the department said.

“Staff are not required to meet targets for debt raising.”

The cost of the robo-debt program is forecast to top $500 million over the next three years, bringing a benefit of $2 billion to the federal budget.