The federal government has offered political staffers the maximum pay rise allowed under government rules, along with new travel allowances, leave for cultural activities and extra pay for staff who speak multiple languages.

The proposed enterprise agreement, which was put to a vote on Monday and is widely expected to be approved, will give approximately 2,000 political, ministerial and electorate staff a pay rise of 11.2 per cent over three years. Four per cent will come in the first year, with 3.8 per cent and 3.4 per cent in the subsequent two years, respectively.

It is the first agreement negotiated under a federal Labor government in over a decade and includes a flurry of new conditions, many of them mirroring the government's economy-wide industrial relations priorities including expanded parental leave, new rules for casuals and family and domestic violence leave.

Sources said the agreement had strong support from staff, especially those from the offices of Labor, Greens and independent MPs, but several Liberal staffers told the ABC they believed the deal was "totally ridiculous" in a broader economy in which "people are doing it tough".

A new allowance of up to $40,000 a year will be available to electorate staff nominated to travel with their parliamentarian, in addition to the usual Canberra travel allowance for advisers.

An allowance of up to $1,500 will go to staff who use a language other than spoken English in their work, including First Nations languages, Auslan and braille.

There will also be three days of leave for any staff to attend significant religious or cultural obligations associated with [their] particular faith or culture.

First Nations staff will also receive one day a year for NAIDOC activities and up to six days over two years to fulfil ceremonial obligations.

Casual staff will receive a pay loading of 25 per cent, up from 20 per cent, and must be paid for a minimum of three hours' work every day they are engaged.

One Liberal source said the deal had effectively shielded highly-paid staffers from what they had lost in the government's redistributed stage 3 tax cuts, which began on July 1.

"The government is cutting the tax reduction for those over $180,000 but insulating advisors on $250,000 a year," the staffer said.

"What's a tradie on $180,000 going to get over three years? Not 11.2 per cent."

The pay rise mirrors what the CPSU achieved for the public service in a separate negotiation with the federal government.

Senior advisers to MPs and senators will be paid between $145,000 and $295,000 in the first year of the agreement. The lowest-paid staff will be paid $72,000, a group which includes local electorate staff, whose workload includes handling constituent complaints and helping constituents interact with government agencies.

The proposed agreement also includes 18 weeks of parental leave for a primary carer, up from 16, and a pathway to 18 weeks for a secondary carer by the end of the agreement in 2027.

Studies assistance has been increased by 50 per cent and "enhanced career transition payments" have been doubled to $1,000.

There is also a one-off payment, which is not included in a copy of the agreement obtained by the ABC but which sources said was in the vicinity of $1,000.

The Liberal source said some of the entitlements agreed to were repeatedly raised and rejected during enterprise bargaining rounds under the former Coalition government.

"Now they have carte blanche because there are more Labor staffers. They've asked for everything but the kitchen sink, and they got everything plus the kitchen sink."

But several Labor staffers told the ABC Liberal staffers had not raised those concerns during the negotiation process.

"The Liberals didn't say a word about this until after the vote had been taken to give them a pay rise. So they wanted to make sure they got the money first, then whinge about it," one senior staffer said.

"They didn't oppose it during the vote. They don't recommend a no vote. They didn't issue any materials that would have opposed this."

The staff ballot on the offer closed at 2pm on Monday and followed months of negotiations between staff representatives, unions and the Department of Finance, which acted on behalf of Special Minister of State Don Farrell.

The outcome of the vote is expected to be confirmed imminently.

The CPSU and Mr Farrell's office have been contacted for comment.