The Senate is considering Abbott government proposals for a scheme to provide payments to workers whose wages were calculated using a tool that the Federal Court found discriminated against people with intellectual disability.

In return for accepting a payment equivalent to 50 per cent of their owed wages, workers, some of whom were paid less than $1 an hour, would give up their right to sue the government for backpay.

The government announced the payment scheme proposal after law firm Maurice Blackburn lodged a class action to recover lost wages for the 10,000 workers.

People with Disability Australia, the Australian Federation of Disability Organisations, the National Council on Intellectual Disability, and Disability Advocacy Network Australia are among the groups that have signed a letter urging senators to reject the bill, and called on the government to negotiate a compensation settlement with the workers.

"We really need the government to man up, own the fact that a wrong has been made and to admit that they've played a part in that," Paul Cain of the National Council on Intellectual Disability said.

Mr Cain said it would be difficult for people with an intellectual disability to comprehend the choices they faced under the scheme and to give valid consent.

The scheme will pay for legal advice and financial counselling for the employees, and accessing this advice would be a prerequisite for accepting a payment.

But Maurice Blackburn's head of employment law, Josh Bornstein, described a provision in the bill that allows the secretary of the Department of Social Services to appoint a person to accept a payment on behalf of a worker as "machiavellian".

Greens senator Rachel Siewert said the bill did not properly compensate underpaid workers and her party was unlikely to support it unless it was amended.

But the bill could pass with the support of Labor, or the Palmer United Party and other crossbenchers.

The Assistant Minister for Social Services, Mitch Fifield, said the scheme was designed to provide certainty to people with disability, their families and carers and for disability enterprises, by providing timely closure of the issue.

"There is a very real possibility that job losses may occur should the scheme not progress, as [disability enterprises] continue to raise concerns about the potential financial threat arising from accruing contingent liability," Senator Fifield said.

A Senate committee report on the bill is due on Tuesday.