Right to disconnect laws passed by the Albanese government will come into effect from August 26, or a year later for small businesses.
They allow employees to ignore work-related contact when they are not working when it's reasonable to do so.
The Australian Council of Trade Unions wants the laws in modern awards - minimum workplace conditions set out by the Fair Work Commission - to clearly state businesses cannot become reliant on contacting workers outside of work because of poor staffing.
Whether a worker is on approved leave wouldn't mandate they cannot be contacted at all, only that it needed to be considered when determining if calling them is reasonable, the union argued.
The same would apply to how staffing levels are organised, it said.
"The existence of a right to disconnect would be of little or no utility at all if the workplace is organised in such a way as to be reliant on contacting employees when they are not working in order to function," it said in a draft submission.
"For this reason we include ... a consideration of whether the employer has taken reasonable steps to eliminate or minimise the need to contact the worker when they are not working."
ACTU president Michele O'Neil says abolishing the right to disconnect would create more burn-out. (Lukas Coch/AAP PHOTOS)
About 70 per cent of workers took calls or checked emails out of hours while one in three were expected to work outside of their scheduled hours, an Australian Services Union survey revealed.
Changes in technology shouldn't undermine employee's being paid for extra work and being able to switch off, ACTU President Michele O'Neil said.
"People deserve to be paid wages for every hour they work," she said.
Switching off helped boost productivity through improved mental health and reduced burnout and stress, Ms O'Neil argued.
The union's submission to the Fair Work Commission comes in light of Opposition Leader Peter Dutton's budget reply speech, where he promised to revert to coalition-era workplace laws.
Businesses have argued not being able to contact workers impacted the flexibility that comes with modern working conditions.
Workers could negotiate job roles with their employer and those who needed to be contacted out of hours were often compensated, Australian Chamber of Commerce and Industry workplace relations director Jessica Tinsley said.
Provisions outlined by the Fair Work Commission shouldn't include rigid definitions, she said.
"Flexibility and choice should be core components, enabling both employers and employees to negotiate specific terms as needed," she said.
"ACCI advocates for a flexible, broad approach to the right to disconnect, ensuring it empowers employees without unnecessarily burdening employers."
