The 90-day probation period should be the default for all new employees, Business New Zealand says.
In a submission to Parliament's transport and industrial relations committee, the business advocacy body said a probation period should be an option employees opt out of when starting a new job, rather than opt in to.
The submission is about the Employment Relationship Amendment Bill, which expands the 90-day probation period to all businesses, rather than only employers with less than 20 employees.
An employee who is fired before the end of the 90-day trial period cannot raise a personal grievance on the grounds of unjustified dismissal.
The trial must be agreed to by both the employer and employee in good faith and in writing.
But Business NZ said since the lack of a signed agreement could render a 90-day period invalid, the trial should be a default when hiring, and employees given the option to contract out of it.
The bill would also make changes to union access to workplaces, communication during collective bargaining, the personal grievance system, employment institutions, and role and enforcement powers of inspectors.
The committee has also taken submissions on the Holidays Amendment Bill, which allows workers to trade in their fourth week of leave for cash, gives employers the right to demand medical certificate for one day sick leave, and changes the way an average day's pay is calculated for holiday purposes.
The unions have strongly opposed the proposed labour law changes, saying it gives employers control and will do nothing for constructive workplace relations.
New Zealand Council of Trade Unions (CTU) president Helen Kelly told the committee extending the 90-day period would remove the human right to appeal against unfair dismissal.
"When they take a job ..., challenging the conditions that your employer might offer you is very difficult."
"We think there is the potential for increase discrimination under these laws. Women who change jobs more, who are more likely to be part-time and casual, will be subject to 90-day provision, again and again, and again," Ms Kelly said.
The CTU does not believe the 90-day probation period will create jobs. Ms Kelly said economic growth created jobs.
The union is also against changes to union access, saying it is a fundamental right for workers.
"We are at a loss as to why the government would introduce this."
It would open the door for bad employers to give excuses to refuse access to unions, Ms Kelly said.
The Engineering, Printing and Manufacturing Union (EPMU) national secretary Andrew Little said making union access dependent on employer consent "treats workers as chattels of business."
"Interfering in the relationship between employees and their freely chosen unions is about saying 'the boss knows best' and shows no respect for the choice made by employees."
"Taking away work rights from Kiwi workers won't close the widening wage gap with Australia.
"All that the proposed changes will do is dampen down current increases in the pay and conditions of workers in unions, as well as the general workplace."
The CTU told the committee it also opposed changes to the Holiday Act such as an employer's right to ask for a sick note for one day leave and cashing up leave.
Ms Kelly said the sick note change is "unfair, and an absolute low trust model."
As for selling holidays, Ms Kelly said "a week's pay is not a week's holiday."
"We think that employees who want pay increases will be told to sell their fourth week leave to make up the gap, and it won't address low wages," she said.