Pauline Hanson’s immigration cuts will cost ‘many billions of dollars’ to implement, former top official says

Former department deputy says One Nation’s hardline approach would require huge funding for enforcement, legal costs and detention centres

Enforcement of Pauline Hanson’s hardline immigration cuts would cost “many, many billions of dollars” and require widespread compliance checks across aged care facilities and some of the country’s biggest construction sites, a former senior immigration official has said.

The One Nation leader on Monday announced plans to cut the number of temporary migrants in Australia by more than 750,000 over three years, targeting international students and family members of skilled migrants.

Business groups, universities, the aged care sector and both Labor and the Coalition all savaged the plan, warning Hanson’s proposals would hurt essential services and the economy.

Policy documents released by One Nation show the party proposes to give unlawful non-citizens three months to leave Australia voluntarily, before enforcement options would be pursued.

Ruling out any general amnesty, One Nation says individuals would face immigration enforcement and a lifetime ban on returning to Australia.

Department of Home Affairs data shows that as of July, the most recent report period, there were 110,898 individuals not granted a protection visa who were yet to be deported. This figure includes people on bridging visas and others seeking a judicial or administration review.

One Nation would pay travel costs for some non-citizens who could not afford to fly home, and large businesses would be subject to increased penalties and enforcement activities for employing illegal workers.

“Cutting off illegal income streams will encourage overstayers to self-depart,” the policy says.

People found overstaying their visas for more than one month would face an automatic three-year ban from the country. Lifetime bans would apply for anyone overstaying for six months or longer.

“Our objective is to make departure requirements enforceable and remove the incentive to break Australian law,” the policy states.

But Abul Rizvi, a former deputy secretary of the immigration­ department, told Guardian Australia the plan would cost the budget “many, many billions” to implement.

He said enforcement activities, legal costs, travel, construction and staffing of detention centres and compensation for wrongful application of the rules would require huge new funding.

“Making threats will make little difference to any longterm overstayer or unsuccessful asylum seekers,” he said.