A major union is fighting the growing trend of ‘hot-desking’ in government offices.

Hot-desking is the practice of allocating desks to workers on a rotational basis, or when they are required, rather than having each worker always at their own desk.

The Australian Services Union (ASU) is taking the Australian Taxation Office (ATO) to the Fair Work Commission (FWC) to protest against a plan to extend a hot-desking trial.

The ATO said it had received positive feedback from many participants in the trial, which had “revealed overwhelming support for the layout offered”.

But Jeff Lapidos from the ASU says many workers do not want hot-desking, and warned it may breach the ATO enterprise bargaining agreement.

“There are many problems with hot-desking,” Mr Lapidos said.

“The first people in on the day get their choice of desk, and the people that come in later in the day don't get a choice so they have to pick up what's left.

“It is not an easy job working in the tax office, and having some comforts from home like photos of your family or friends or having sporting memorabilia helps people get through the day.

“It's clear that their real purpose is to reduce accommodation costs, even if it is at the expense of productivity.”

The ATO says hot-desking gives staff “more efficient access to a wider range of facilities” and that staff still have places to store personal items.

Libby Sander from Bond Business School said hot-desking saves money, but the productivity benefits can be hard to pin down.

“One of the problems with most modern offices is that a lot of the time, quite a significant percentage of staff are not in the office — they're on annual leave, they're out at meetings, they're doing various other things,” Ms Sander told the ABC.

“So organisations have figured out through hot-desking you can save around about 30 to 40 per cent of your lease costs by reducing the footprint of your workplace.

“We're also finding that people are not necessarily communicating more with their colleagues, but are actually becoming quite indifferent to them.

“So they think; ‘Well if I'm not going to sit next to you tomorrow, I might as well not be bothered saying hello to you really, because I might never see you again’, which is an unexpected, opposite outcome from what the organisation was intending.

“But because it's still relatively new in terms of it being a widespread practice, we haven't seen many open disputes as we are now seeing with this particular case between the ASU and the ATO.”