Broadcaster Hilary Barry says she's got some bad news for the women of New Zealand: from today they'll be working for free.

The TVNZ Breakfast host has added her voice to increasing calls for greater pay parity in New Zealand, with the Council of Trade Unions (CTU) also making a public statement on the matter today.

"Dear Women of NZ, I've got some bad news for you. From today until the end of the year you're working for free," Barry said on Twitter this morning.

CTU vice-president Rachel Mackintosh explained that the 13 per cent gender pay gap meant the boss was essentially getting free labour out of women in paid work from today until January 1.


"Māori women collectively started working for free on the October 8. Pasifika women are effectively unpaid for over a quarter of the year - their employers started taking free labour, on average, from September 21," she said.

Mackintosh said New Zealand law already dictated that taking this unpaid labour from women was illegal.

"The free ride is about to end," she said. "We have three parties in government now who have committed to putting the agreed equal pay principles into the current law and not creating additional hurdles for women. This will create a swift and clear legal pathway for women to claim the pay that's rightfully theirs.

"Most people in 2017 would agree that paying women fairly for the work they do is overdue."

The CTU had launched a "countdown clock" for November 14, 2018, "So we can look back together in a year's time and celebrate having fair equal pay law that's working well for all women", Mackintosh said.

According a 2017 report on the gender pay gap by the Ministry for Women, traditional drivers such as type of work, family responsibilities, education, and age no longer explained the majority of the divergence.

"In fact, around 80 per cent of the gender pay gap is now due to 'unexplained' factors, which the ministry views primarily as behaviour, attitudes, and assumptions about women in work, including unconscious bias," the report says.