The Labor Party and unions have slammed new legislation giving a one-off amnesty to employers who haven’t paid workers’ superannuation entitlements.

Under the legislation passed on Monday, employers would need to come forward voluntarily, without direct prompting from the tax office, and pay all employee entitlements.

Penalties and administration fees would be waived to allow payments to be tax deductible in the same manner as regular super contributions.

Employers who failed to voluntarily come forward during the amnesty face fines of up to double the unpaid entitlements.

The Coalition legislation was backed by crossbench senators, while Labor and the Greens voted against it.

Australian Council of Trade Unions president Michelle O’Neil said superannuation formed a major part of the wage theft crisis gripping the country.

“This law will recover a tiny fraction of the billions in super estimated stolen since the beginning of the system and will do nothing to change behaviour in the business community,” she said.

Unions want the right to superannuation included in the National Employment Standards so repayment can be more easily pursued.

“This is a shameful act by a government which it seems will stop at nothing to cater to employers at the expense of working people,” Ms O’Neil said.

Labor frontbencher Jenny McAllister said the amnesty was unfair.

“If you are an employee and you steal from your employer, you have the book thrown at you. The police will come around to your place,” she said.

“But, under this government’s plan, if you are an employer and you want to steal from an employee, no worries, so long as you say sorry.”

Liberal Senator Andrew Bragg said Labor opposed the measures because union-linked industry super funds rejected any changes to the system.

“There is no other way that these workers will get their super back. This is the only chance,” he told Parliament.

“Voting against it and arguing against it is arguing against the workers that people on the other side of the chamber purport to represent, which is just extraordinary.”

The measure is expected to recover $160 million in unpaid retirement savings, with 7000 employers already coming forward and the same amount expected to own up once the bill passes.

-with AAP