Centrelink, Medicare and child support staff will walk off the job on Friday over a long-running pay dispute.
The human services staff have been stuck in negotiations for more than three years without a pay rise and the department is refusing to budge, CPSU national secretary Nadine Flood says.
"All they want to do is hold on to rights and conditions that have been in place for many years and allow them to balance their working and family lives," she said ahead of the strike, to take place between 1.30pm and 8.30pm (AEDT).
Customer payments will not be affected by the industrial action, but there will be less staff in service centres and manning the phones, Human Services department boss Hank Jongen says.
He encouraged customers to use online and self-service options during the seven-hour strike.
Mr Jongen said the department won't be swayed over the pay negotiations, so more industrial action can be expected.
