Health Minister David Clark will today sign a $173.5 million pay equity settlement for mental health and addiction support workers that brings them into line with care and support workers.

Around 5000 workers are in line for a pay rise after the Government extended the landmark Care and Support Workers (Pay Equity) Settlement Act after a claim was lodged by the Public Service Association and E tū unions with the Employment Relations Authority.

Clark has estimated nearly half of the workers will get an increase of more than $3 an hour and for 1000 it will be a more than $5 per hour increase, backdated to July 2017.

"This agreement puts right a problem created by the previous government which deliberately excluded mental health and addiction workers from the Care and Support Workers settlement," Clark said in June.

The $173.5 million settlement extension will be implemented over five years and funded through an increase to the health budget.

The Care and Support Workers (Pay Equity) Settlement Act increased the pay rates of 55,000 care and support workers in aged and disability residential care, and home and community support services.

It was the case of rest home worker Kristine Bartlett that was the catalyst for the previous National government's $2 billion pay equity settlement.

"Our members in mental health and addiction support were unfairly left out of the original settlement," PSA assistant national secretary Kerry Davies said.