A ballot of more than 11,000 departmental employees has returned an 81 per cent no vote to the wage offer of 2 per cent a year, the second time Immigration staff have rejected a proposal in the current protracted round of bargaining.

The result means that strikes will almost certainly hit the nation's international airports during the busy Easter period at the end of March.

Immigration is the latest in a string of large departments to have rejected proposals, following no-votes at the Tax Office, Human Services and last week's narrow rejection of a deal at Defence. Staff at Prime Minister and Cabinet also voted down an enterprise agreement last month.

Senior Immigration official David Leonard broke the news of the vote's result to his colleagues on Monday morning.

"A total of 11,201 employees (81.2 per cent) voted in the ballot. Of those who voted, 80.9 per cent have voted 'no'," Mr Leonard wrote.

"We remain committed to working with you to consider refinements to the offer in keeping with the government's framework.

"I will come back to you to discuss next steps, including timing for a further round of negotiations in the near future."

The Community and Public Sector Union claimed the result on Wednesday as another victory in its campaign against Coalition's approach to pay and conditions in the public service.

"An 81 per cent no vote from the Immigration and border protection workers who keep Australia safe is another stinging rebuke of the government's unworkable and unreasonable approach to public sector bargaining," the union's national secretary, Nadine Flood, said:

"This strong No vote is no surprise, given the dodgy agreement that DIBP management had put on the table.

"These workers are ordinary mums and dads, yet they still face losing rights and conditions that allow them to balance long and irregular hours with their family commitments, and some still face having their take-home pay cut," she said.

"This result shows how deeply dissatisfied these workers remain and why they're preparing to continue their campaign of strike action over Easter to pressure the government to engage meaningfully on changing the bargaining policy to allow fair and reasonable outcomes.

"It's still not too late for Prime Minister Malcolm Turnbull and (Employment) Minister Michaelia Cash to heed the clear message that's been sent by DIBP workers and staff who've voted No in other agencies including Human Services, the Tax Office and Defence."

The 24-hour strike, planned by Immigration and Border Force workers for Easter Thursday, will be preceded by strikes by public servants at the Tax Office, Medicare, Centrelink, the Child Support Agency and the Bureau of Meteorology.

Bureaucrats at the Department of the Prime Minister and Cabinet and the Bureau of Statistics are also planning to join in the 24-hour strike on Monday, March 21, in what will be the most comprehensive industrial action seen so far in the dispute.

There could be further escalation with a three-week campaign of rolling airport strikes over the Easter school holidays being considered.