Service Australia's Tuggeranong office has again been listed as a COVID-19 exposure site after a positive case visited the building at the weekend.
It comes nearly a month after a separate individual visited the federal agency's Caroline Chisholm Centre while infectious.
Anyone who was on level three of the building's north wing between 8.20am and 5pm on September 15 or between 8.30am and 1.30pm on September 14 is now considered a casual contact and must get tested and isolate.
The office's Calypso Cafe is also a casual contact location on September 15 between 12.20pm and 1.10pm.
Anyone who visited anywhere in the building last Tuesday and Wednesday must monitor for symptoms.
Services Australia general manager Hank Jongen said the agency received confirmation from local health authorities that a staff member had tested positive.
He said deep-cleaning on the impacted areas had been undertaken and affected staff were now isolating and getting tested.
A limited number of staff remain working from the Tuggeranong office, he said.
"Staff in the office have designated desks and follow COVID-Safe workplace practices, including wearing a mask while in the office," Mr Jongen said in a statement.
"Services Australia is providing essential pandemic support to Australians while adhering to the health advice of relevant state and territory health authorities. The wellbeing of our staff and customers is our top priority and we've put in place arrangements to keep them safe.
"When stay at home orders are put in place, the agency works to accommodate working from home arrangements where it is reasonably practicable to do so."
Last month, another public servant tested positive to COVID-19 having been in the office building over two days while infectious.
It followed shortly after calls from the Community and Public Sector Union to vaccinate frontline Services Australia staff urgently and invest in more equipment to make working from home possible for all staff.
In a letter to Prime Minister Scott Morrison and Government Services Minister Senator Linda Reynolds, staff requested 10,000 mobile phones and fast-tracked technical upgrades to enable more public servants to work from home during lockdowns and to reduce the risk of the virus spreading.
A small number of staff are still required to attend the office while in lockdown due to equipment shortages.
Level seven of the Department of Education, Skills and Employment's office in Garema Place was also listed as a casual exposure site over the weekend.
Anyone who attended the seventh floor between 8.40am and 4.45pm on September 10 is considered a casual contact.
Others who visited any other level within the building on 140-180 City Walk must monitor for symptoms.
Earlier this month, an Australian Bureau of Statistics staff member tested positive for COVID after working at one of the agency's offices in Belconnen.
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