Australian Taxation Office workers in Melbourne and Queensland can expect building renovations to bring layouts forcing them to look for a new desk each day, the Australian Services Union representing tax officials says.

After the ATO's hot-desking plans for offices in Gosford and Docklands survived a fight at the Fair Work Commission, buildings in Melbourne suburb Moonee Ponds and Townsville are believed to be next on the list for hot-desking.

The Tax Office says it has not settled on a fit-out for the offices but confirmed it will review layouts for the sites, and at others nearing lease expiry in Brisbane suburbs Chermside and Upper Mount Gravatt.

ASU official Jeff Lapidos warned a hot-desking "tsunami" would spread across the ATO's offices when their leases expired and the agency redesigned their fit-outs.

"The Tax Office will get away with it unless the ASU and our members ensure our voices and those of the staff more generally are heard and heeded," he said.

"The ATO has made it clear to the ASU that it intends hot-desking at each of the renovated Moonee Ponds office, the new Townsville office and whatever the decision will be for the Chermside and Upper Mount Gravatt offices."

Mr Lapidos said that Moonee Ponds would have 50 more desks than staff under Tax Office plans.

"Surely this will allow everyone to have their own desk," he said.

"It will be first in before 7am who will get first choice of desk. Later starters will get the left overs.

"The ATO's plan is consult, consult and consult some more and then do what it wants."

A Tax Office spokesman said its new fit-outs would meet staff needs and that it had no plans to convert all offices to "activity-based" workplaces.

"Similar fitouts are being used extensively in many leading public and private sector organisations locally and across the world," he said.

"The fit-out provides modern flexible workspaces and the technology to suit the different types of work in the site."

Unions have fought the hot-desking roll-out at the ATO, arguing it was not a smart or cost-effective way to organise offices, and that it threatened morale and productivity.

Hot-desking has been widely adopted in the private sector by firms hoping to reduce wasted space and build teams.

But the trend has caused frustration for many employees who say it disrupts their work and poses health and safety problems.

Despite the Tax Office's win at Fair Work in December, the stoush may have been a warm-up as Mr Lapidos warns the union will need members in Moonee Ponds to help it prepare a case at the industrial umpire against hot-desking proposals and the "tiny desks" they bring.

"The ASU’s leadership does not want hot-desking at Moonee Ponds and we don’t want the tiny desks the Tax Office put in place at level eight at the Docklands office, which is replicated at the new Gosford office," he said.

More leases are due to expire across Canberra, Sydney, Victoria and Perth offices between 2021 and 2027.

The ATO said it consulted staff and industry on the furniture it used.