Trade unions are embarking on a campaign to protect workers from 90-day work trials by excluding the new requirement from collective contracts.
The probation period for all new workers is part of new labour laws, which also restrict union access to the workplace, and come into effect in April.
The country's biggest private sector union, the Engineering, Printing and Manufacturing Union, is part of the campaign against the new laws.
National secretary Andrew Little says the union expects many employers will agree to the request, but there will be additional conflict during collective bargaining for those who do not.
The Service and Food Workers Union has signed collective contracts with the TAB and some aged care and residential services companies who have agreed not to include the trial provision.
National secretary John Ryall says the large employers the union has dealt with are happy with the status quo, and agree that if they're going to dismiss people there needs to be a clear and fair process.
The Public Service Association says collective bargaining in the state sector will be more difficult this year.
An email sent by the State Services Commission's deputy commissioner Peter Brown in December says state sector bosses should not "contract out of" the probationary period.
PSA national secretary Brenda Pilott says the commission must inform its members about new laws. However, she says it is taking a hard line and it will be difficult for state sector employers to ignore the directive.
A spokesperson for Labour Minister Kate Wilkinson says removing the 90-day trial from collective contracts could stop new workers being given a chance at a job and the new laws offer opportunity for new workers and the state sector should use them as it sees fit.