Federal Labor will try to turn around its horror start to the year by reigniting the debate on workplace relations law.

The government's tough start to the election year has included the arrest of Labor-turned-independent MP Craig Thomson, Prime Minister Julia Gillard's controversial captain's pick of Nova Peris as an NT Senate candidate and the resignation of two senior ministers.

Ms Gillard will be aiming to shift the focus when she announces plans to change industrial relations legislation later in the week.

The changes, which she flagged on Sunday, will give new parents returning to work more flexibility, while also providing roster workers with more certainty.

Labor MPs will no doubt use it as an opportunity to remind Australians that they successfully scrapped the Howard government's controversial Work Choices laws.

They'll also likely call into question Opposition Leader Tony Abbott's intentions to change IR laws, despite his past comments that Work Choices was "dead".

Parliament will resume debating the government's National Disability Insurance Scheme (NDIS) laws while senators will have a chance to quiz department officials during budget estimates.

The coalition and the Greens will look to probe treasury officials on why the government decided to abandon its promise to deliver a budget surplus in 2012/13, during an economics estimates hearing on Wednesday.

They'll also quiz officials about Labor's Mining Resources Rent Tax (MRRT), which has only raised $126 million in its first six months of operation.

Border protection will be back in focus on Monday when immigration department officials front a budget estimates hearing.

Opposition senators will question why boat arrivals have continued unabated despite Labor's toughening of its policies.

The Greens will also point to living conditions in processing centres on Nauru and Papua New Guinea's Manus Island, while questioning why it has taken so long to process asylum seeker claims.