Up to 80 staff at Canberra's betting agency ACTTAB will lose their jobs by the end of the year according to the union.

News of the job cuts was broken to staff this morning at a meeting with Tabcorp management.

The ACT Government sold ACTTAB to Tabcorp Holdings last year for over $105.5 million.

The profits made from the sale went towards infrastructure projects in the ACT including the Capital Metro light rail project, via the Federal Government's asset recycling program.

United Services Union organiser Rudi Oppitz said employees would be let go as early as October.

He said the cuts would dismantle the company.

"At least 70 to 80 jobs will go," he said.

"They are devastated.

"They know what the economy is like in Canberra."

Seven ACTTAB branches around the capital will also be closed, with the remaining eight branches turned into agencies.

The name ACTTAB will also disappear, with what is left of the agency to be known as Tabcorp.

"When the ACT Government sold ACTTAB, we fought very hard to stop that sale taking place," Mr Oppitz said.

"We were told by the Government and also by Tabcorp that this was going to be a golden opportunity for existing employees for job security and that there was the potential for new jobs to be created in Canberra.

"Now we find that's not the case."

Mr Oppitz said the remaining staff would be employed as casual workers.

In a statement, Tabcorp said most of the jobs affected were casual roles.

"As a result of the ongoing integration of the businesses and systems of ACTTAB and Tabcorp, a number of ACTTAB roles will be phased out over the next six months," the statement said.

"We will maintain a core head office in Canberra."