Changes to the Equal Pay Act come into force today, with the government claiming they give employees in female-dominated occupations a clearer pathway to pay equity.
The Council of Trade Unions said there is now no excuse not to start pushing forward fair pay claims for women in industries that have been typically undervalued.
The council's president, Richard Wagstaff, said there will likely be a number of claims raised in the next year as members and employers become more acquainted with the new law.
"We will be more relaxed and more practised at actually applying the law and people will understand how it works.
"We need to get on with that because there's been significant historical undervaluation of work held by women for far too long of course and there's no excuse for not getting on with it."
But the organisation representing early learning centres said it is the wrong time to launch pay equity claims against them.
Early Childhood Council chief executive Peter Reynolds said a number of centre owners are receiving legal letters from unions and private claimants for pay equity.
He said with the Covid-19 crisis, child care centres are in a difficult position with their revenues well down, and many are doing their level best just to keep their doors open.
Reynolds is accusing the government of taking a 'bull in a china shop' approach to pay equity.
The primary and early childhood union, NZEI, disagrees saying the act opens up major opportunities for its members.
NZEI is raising 10 pay equity claims to benefit thousands of women across the sector.
A spokesperson, Virginia Oakly, said women are still paid on average $4 an hour less than men and this law makes sure they can be fairly paid.
Oakly said the 10 claims include teachers, school librarians, science technicians, administrators and other support staff.
Minister for Workplace Relations Michael Wood said Covid-19 has highlighted the many workers who do important work but who are not well or fairly paid.
The new law establishes a clear process for unions and individuals to raise a pay equity claim directly with an employer, he said.
He said it encourages evidence-based decision-making, rather than relying on an adversarial court process.
"Most people do not want to take their employer to court if they can avoid it. The new process aligns with the bargaining process in the Employment Relations Act 2000, and encourages collaboration and evidence-based decision making to address pay inequity, rather than relying on an adversarial court process," Wood said in a statement.
Minister for Women Jan Tinetti said changes to the act will impact the lives of those working in some of the lowest paid occupations.
"Employers already have a duty not to pay people differently on the basis of sex. No one should be paid less just because they work in a female-dominated occupation," she said in a statement.
"Achieving pay equity and putting more money in the hands of the lowest paid workers has a significant positive impact on their lives, and is likely to have flow-on benefits to their whānau and the wider community," Tinetti said.