Rudd- and Gillard-era Treasurer Wayne Swan and former Trade Minister Craig Emerson will give evidence to the Fair Work Commission after the agency's dispute with staff over a new workplace deal went to a rare arbitration process last year.

The Labor party figures will join 16 other witnesses for Community and Public Sector Union members at the hearings including anti-domestic violence advocate and researcher Cathy Humphreys and workplace relations academic Michael O'Donnell.

More than 97 per cent of staff surveyed at the Department of Immigration and Border Protection told the CPSU that the protracted negotiations had hurt their family finances by freezing their wage increases.

Union survey results showed 96 per cent of staff believed the marathon bargaining dispute had sunk morale.

Mr Swan will also submit written evidence to the Fair Work Commission after accusing the Coalition government of 'shafting' its own rank-and-file public servants and delivering pay rises to bureaucracy bosses.

He unleashed an attack on the Turnbull government in September saying it had contempt for people working in Commonwealth departments who lived in fear of their jobs being casualised, outsourced or privatised.

The department's three-year fight went to arbitration after a proposed enterprise agreement was rejected three times, with a no vote of more than 90 per cent in September 2015, 82 per cent in March 2016 and 81 per cent in November.

It is believed to be the first Fair Work Commission arbitration involving an APS department under current industrial relations legislation.

Immigration will have until late June to make its submissions before the arbitration hearings, which start on July 19.

After hearings the Fair Work Commission will consider its decision and make its workplace determination.

An Immigration Department spokeswoman said it continued to engage with the arbitration process and that further comment would not be appropriate.