All staff will vote on Wednesday on whether a 2 per cent pay rise scheduled for July should be deferred for 12 months in order to save $6.75 million over six months.

In an open letter to Vice-Chancellor Brian Schmidt, the ACT Casuals Network claims casual and sessional workers on low incomes will be disproportionately affected by the pay freeze and job cuts. It has been signed by 131 staff members and 215 students.

Casual tutor and doctoral student Bianca Hennessy said she was draining her savings and applying for JobSeeker to make ends meet.

"My peers who I have a lot in common with but went into public service or other areas are buying apartments, they're planning to have families and I'm filling out a JobSeeker application and working out how to live for the next few months."

Ms Hennesy found she was earning a similar amount in a retail job she held ten years ago and didn't see any prospect of getting a permanent job at the university, with the stability and leave entitlements that came with it.

"I care about my students so much but now I have to start a whole new career at age 30 and I don't get to live a career that I thought was possible when I started."

Casual course convener Dr Joe McCarthy said when academics retired they were usually replaced by a casual staff member.

"Casual convening has become an insidious employment practice at ANU and it's been getting worse," he said.

About 30 per cent of ANU staff are on a casual or fixed-term contract but it is also unknown how many of these contracts won't be renewed as the university seeks to reduce its salary costs to make up for a $225 million shortfall.

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Dr McCarthy said casual conveners were paid for six hours of preparation for a two-hour lecture but that this was impossible to achieve once administration work, student consultations and updates to course material were factored in.

Casual tutors are allowed two hours to prepare for a tutorial, which involves course readings, watching a two-hour lecture, planning the class, answering student emails and administration.

Dr McCarthy said the ACT Casuals Network was not calling for the end of casual staffing but for better conditions and pay after been used to offset other costs in the university for many years. They are also calling for more transparency about how funding is allocated.

"If I had known what I'd be experiencing now, even though I love teaching, I wouldn't have done a PhD," he said.

In response to the open letter, an ANU spokesperson said the university was working hard to save as many jobs as it could in the face of a major economic disruption.

"Any pay deferral will help save jobs. We continue to consult and work with our entire community on these important measures."