The Department of Social Services' new national headquarters at the corner of Athllon Drive and Soward Way will be home to 2,500 staff.

It was opened by Senator Zed Seselja, the assistant minister for social services, at a ceremony on Tuesday morning.

The six storey, 38,400 square metre building was developed by the Cromwell Property Group and is estimated to be worth $260 million.

Construction began in June 2015 and cost $172 million.

Mr Seselja has previously lauded the possible economic impact the project would have on the suburb of Tuggeranong.

"This development will have a positive economic impact on the local community and will deliver long-term savings to the government through reduced property operating expenses and improved fit-out flexibility," Mr Seselja said during a turf-turning ceremony in 2015.

"I fought hard to keep the Department of Social Services at Tuggeranong and I'm really pleased that this strong presence will now remain at the Tuggeranong town centre."

Damian Horton, Cromwell's head of property, said the project had been "exciting and rewarding".

"We have worked closely with the Department of Social Services throughout the project, from conception to delivery, so we are honoured to officially welcome them today," he said.