Casual workers could be offered permanent roles after 12 months under a Fair Work Commission proposal, which unions say will help tackle an “epidemic” of insecure work.

In a decision published on Wednesday, the commission said a “casual conversion provision” was necessary to make sure employers did not keep people on casual contracts indefinitely.

The commission’s draft proposal would require businesses to offer casuals a permanent role if they had been working a pattern of hours equivalent to a full-time or part-time position.

“Some employers do engage indefinitely as casuals persons who under the relevant award provisions may be, and want to be, employed permanently,” the commission said its decision summary.

The ACTU had wanted casual workers to be able to shift to permanent roles after six months, but said the commission’s decision “plugs one small hole in this epidemic” of insecure work.

“Anything that improves the lives of working people is a step forward. It’s a win,” secretary Sally McManus told reporters.

The decision covers 85 awards, which McManus said included hospitality, retail, manufacturing, community services, child care and farming sectors.

The commission said businesses could refuse to move casual workers to permanent roles if doing so would require a significant adjustment to the employees’ hours or if it was clear their role would cease to exist.

It also reached the provisional view casuals under 34 awards – which did not have a minimum on shift length – should be called in to work for no fewer than two hours.

The ACTU had pushed for shifts of at least four hours for casual and part-time employees.

Australian Retailers Association (ARA) executive director, Russell Zimmerman said while the decision gives retail staff employment security, the ARA are concerned the decision will reduce flexibility for retailers.

“We acknowledge Fair Work’s decision today, however we fear this verdict will significantly impact retailers as casual’s flexible hours are essential to the industry,” Zimmerman said.

“Given the current change-of-hours rules around part-time employees, there is a continual need for casual employees and their flexible working arrangements.”

The ARA said it believes the decision will only be operationally viable if retail employers are able to offer part-time workers additional hours without incurring overtime penalties, as the procedural requirements for changes to the rostered hours of part-time employees can be unrealistic for retailers.

“The ARA believes that if there were flexibility in the hours of part-time employees this decision might have made sense, but the retail industry experiences peaks and troughs in trade which are an impediment to offering fixed hours for part-time employees,” Zimmerman said.

Australian Chamber of Commerce and Industry deputy workplace relations director Alana Matheson said members strongly opposed the unions’ plan for a minimum four-hour shift.

“(It) would have made it harder for businesses to give after-school jobs to students,” Ms Matheson said.

“This was an anti-jobs proposal from the union movement – it was important that it be rejected not only from the perspective of business but for job seekers and the underemployed.”

The commission will hear submissions from business and unions about its draft proposals.

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