About 28 per cent of public servants were working from home in the two weeks to October 9. The figure was down from 32 per cent in the previous fortnight, before the APS commission directed the bureaucracy to bring its staff back to office buildings.

Central Queensland University academic Linda Colley, who researches public administration, said she was surprised at how quickly the number had dropped after reaching about 64 per cent in August.

The public service commission's direction for Commonwealth employers to start making arrangements for all employees to return to the office was only made in September, she said.

"It suggests half of those people working from home have already transitioned back to the workplace in some form before the end of September, and then it kept decreasing into October," Associate Professor Colley said.

The number of bureaucrats working from home was still high in comparison to pre-pandemic levels, which were about 15 per cent.

That raised questions, including about the influence of the Victorian lockdown on the number of bureaucrats still working from home, and the capacity of offices as COVID-19 restrictions reduced space for staff, she said.

Among the public servants back in their regular workplaces, some spend parts of their week still working at home. Some Commonwealth office buildings, with social distancing rules applied, fit fewer bureaucrats than before the pandemic.

The number of federal public servants back in office buildings also differs across states and territories, each giving health advice according to their own coronavirus case numbers.

Agencies have not been uniform in how they bring staff back into regular workplaces, either.

At the Department of Agriculture, Water and the Environment, building occupancy levels across all sites averaged 50 per cent by the end of September.

Some reached 70 per cent, and others returned to pre-coronavirus occupancy levels.

"Over the next four weeks occupancy rates are set to increase across sites where low community transmission is recorded and state based health advice allows, in line with APS Commission guidance," a department spokesman said.

About 90 per cent of Canberra-based staff at the Department of Industry, Science, Energy and Resources worked in the office in the two weeks to October 13.

The Department of Education, Skills and Employment averaged 60 per cent of staff working from its buildings in September, except in Victoria, where its offices are closed.

That month, about 45 per cent of Health Department staff were also in the office on any one day, the remainder either working remotely, on leave, or in the case of part-time workers, not rostered on.

Most staff work part of the week in one of the department's offices and part of the week remotely.

The Australian Taxation Office said it was planning a staggered return, starting this month.

Staff working in office buildings are told to avoid crowded lifts and foyers, and to maintain 1.5 metres in shared spaces such as kitchens and utility bays. Public servants visiting co-workers at their desk, or talking to a colleague sitting next to them, have to maintain appropriate social distancing.

"As more staff start to return to the office, additional cleaning of high-touch points and other surfaces will be included in the cleaning protocols and monitored to ensure a clean and safe environment," the Tax Office's spokesman said.

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One of Canberra's largest public sector employers, the Home Affairs Department, said about 50 per cent of its ACT staff worked remotely on average in the two weeks to September 28.

It planned to bring Canberra-based staff back to their usual workplaces from October 19 to November 16, staggering shifts to avoid offices overcrowding.

In Victoria and NSW, which have higher numbers of daily new coronavirus infections, Home Affairs staff continue to work from home in line with state guidelines.

Community and Public Sector Union national secretary Melissa Donnelly said although coronavirus case numbers were down, physical distancing requirements and appropriate safeguards were still needed.

"Plans need to consider the difficulties that public transport, access to workstations and lift usage particularly in large buildings," she said.

"For example, some Canberra offices present unique issues in relation to social distancing and access to floors via lifts."

However, the agencies bringing staff back to office buildings were generally taking a sensible approach in approving requests to keep working from home, she said.

Ms Donnelly said public servants had excelled while the majority of its workforce was working from home during the pandemic.

"Managers have supported and endorsed its effectiveness, and workers want to see it available into future," she said.

Associate Professor Colley, one of two authors of a study this year into changing public service attitudes towards working from home, said the pandemic had removed some resistance from managers.

"But it's too early to tell whether attitudes have changed permanently," she said.

"It remains to be seen whether organisations are ready to cement that change in an ongoing form."