Labor’s leadership team of Bill Shorten and Tanya Plibersek pioneered the “robo-debt” data-matching system Centrelink is using to target current and former welfare recipients for apparently not declaring their income properly — but they now argue it should be suspended.

The automated system of matching income data from the tax office and income as reported to Centrelink to identify discrepancies was announced in a joint release­ by the then minister for human services, Ms Plibersek, and the then assistant treasurer, now Opposition Leader, in June 2011, adding an extra $71 million to the budget. The release said the “tax garnishee process had been carried out manually once a year for the past 15 years and involved a significant amount of time on the part of departmental officers”.

“The automation of this process will free up resources and result­ in more people being referred to the tax garnishee process, retrieving more outstanding debt on behalf of taxpayers,” Mr Shorten said at the time.

The measure was forecast to “identify” 63,000 former customers over four years in addit­ion to the 43,000 captured in 2009-10.

The amount of debt recovered from welfare letters in 2010-11 was $1.8 billion, jumping to $2.2bn in 2013-14.

Under a dramatic escalation of the same system, the Coal­ition plans to recover almost $4bn in debt over the next four years, partly helped by a bipartisan vote in parliament that extended the statute of limitations on old debt that can be chased.