SUDBURY -- Some employees at Canada Revenue Agency’s Sudbury, Ont. tax centre building are being told to stay home from work effective Monday, March 16, sources tell CTV News.

CTV News has learned that all non-essential employees are not to report to work.

A recording obtained by CTV News, taken Sunday night by a CRA employee, details the new guidelines:

"Only CRA employees who are physically required to conduct critical services are allowed to be on CRA premises. All other employees are to remain at home."

It is unclear which positions are deemed essential, but many workers say they received a call from their supervisor asking them to report to work.

CTV News spoke to Marc Briere, president of the Union of Taxation Employees, who says the union was notified late Sunday night about the issue and that workers with Tax Centre operations have been deemed critical, while the Tax Service Office employees have been deemed non-critical.

The Sudbury facility employs thousands of people and is the largest in the country.

Briere says 2,100 people are still working at the building and about 300 are working from home and teleconferencing in some way. He says anyone asked to stay home will still be paid.

Union officials say there have been issues of space in light of the social distancing recommendations from public health officials.

Some employees are not happy there's not enough space between workstations and some are upset about the desk sharing, saying that they are not getting clean facilities.

There are two shifts every day, a day shift and an afternoon shift, and activity within the building is ramping up because it's getting busy with tax season.

"To me, sharing a desk and keyboard with an afternoon shift stranger is not a safe work environment. So, it's just not worth it to me to show up for work. I told my team leader by phone this morning that I will not be coming back for at least two weeks. Now, with the second COVID-19 case here in Sudbury, I highly doubt I will return at all," an employee test CTV News.

The union says CRA management has been flexible with childcare leave and has ordered disinfectant wipes and sanitizer supplies for the facility.

Michael Aubry, communications officer at Public Service Alliance of Canada, confirms the Treasury Board Secretariat sent a memo to all staff Sunday night calling for all non-essential staff across the federal public service to work from home.

"Employees that are considered essential are those whose presence in the office is deemed essential to public safety. That means border officers, a minimum number of engineers in boiler rooms, Coast Guard rescue teams, etc. Each department has a list of essential services drawn up that the union must sign off on (the same way we draw up essential services during a strike or lockout)," said Aubry.

CTV News has not confirmed the news directly with CRA management.