Nine thousand tax officials had made the move from Australian Taxation Office buildings by last Friday, using new technology for working remotely.

The mass relocation is growing each day, coinciding with the tax office receiving one of the largest tasks as the government uses stimulus measures to stem the worst economic fallout from COVID-19 restrictions.

Call centre work was happening outside the office last week too, as 500 ATO employees received calls remotely.

However unions representing tax officials warned the rapid change to working from home, and large workloads, could lead to problems.

Australian Services Union official Jeff Lapidos said there were ATO employees working from kitchen counters, dining room tables and couches. Some were using laptop computers for long periods.

Mr Lapidos said the ATO would need to spend money to make sure staff had the right equipment, otherwise it would risk eventually facing workers compensation claims.

Community and Public Sector Union national deputy secretary Beth Vincent-Pietsch said the volume of work for ATO staff could not be underestimated.

"Our economy depends on quick implementation, and the ATO are confident that it is manageable with existing staff and some new recruits, but the CPSU is calling on the government to monitor the workload of ATO workers, and be ready to hire even more new public sector workers to assist in this critical front-line work," she said.

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Public service commissioner Peter Woolcott on Tuesday said the federal bureaucracy was taking a "deliberate and phased" approach to working from home.

However despite urging on Sunday that as many APS employees as possible should be supported to work from home, staff at Defence, Services Australia and some smaller agencies continue to say they have had to attend the office despite being able to work remotely.

Professionals Australia ACT branch director Dale Beasley, representing Commonwealth scientists and engineers, said many staff were buoyed at the weekend by the commissioner's comments about home-based work.

"But as the days have passed we're still seeing an unnecessary number of staff being required to attend the office to perform work they could, and should, be doing from home," he said.

"Employees are genuinely fearful of getting sick as a result of their commute on public transport, so to a degree it doesn't matter what social-distancing measures are in place at the office."

Labor public service spokeswoman Katy Gallagher wrote to Mr Woolcott following reports some agencies were ignoring the public service commission's comments on Sunday that Commonwealth employers should facilitate working from home.

"If there is a way to reduce the numbers of staff in the office this should be aggressively pursued," she said.

Mr Woolcott said every agency had "for some time" prepared for work-from-home arrangements with trials of flexible arrangements and by testing IT.

Some agencies were able to offer greater levels of working from home, or move to widespread working from home more quickly than others, he said.

Mr Woolcott said the public service commission's latest announcement on working from home also reiterated that agencies were to ensure a safe working environment for those still in their usual workplaces.

"Agencies were already doing so, but it was important to put that issue to rest given concerns being raised," he said.

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