A swarm of Inland Revenue Department and Ministry of Business, Innovation and Employment staff are marching for higher pay in central Wellington and Auckland.
The protesters started making noise at 1.15pm at the intersection of Queen and Victoria Sts, chanting that "we want fair pay and we want it now".
PSA assistant secretary Basil Prestidge said: "We are protesting here trying to get a fair deal with IRD and MBIE."
"Wage rates have been suppressed and held down relative to other agencies. Even people doing the same jobs get different rates of pay.
"They have got a rate for the job which is too low and people aren't even getting paid that rate."
The number protesting at three points of the intersection has swelled to about 120 as more members arrive for the two-hour strike.
They are making a racket, hitting protest signs with sticks and blowing whistles.
Last month PSA claimed that Inland Revenue's IT system could not process the new Best Start tax credit which kicks in next week as part of the Government's Families Package and it would have to be done manually.
PSA national secretary Erin Polaczuk said last month that members took their jobs very seriously and they're trying desperately to keep the system on track while IR presses ahead with its Business Transformation project which will see one in three staff "let go" by 2021.
"It starts on 1 July, and members are told they will have to process this manually, drastically increasing their workload," Polaczuk said.
In Wellington ralliers started to gather at Midland Park in for the march.
They were holding signs saying "toot for support" and "Born in the PSA".
A brass band played while strikers waved flags and organisers handed out fliers with chants on them.
Cheers and applause rang out in response to tooting from supportive drivers going past on Lambton Quay.
The band played Money Money Money by ABBA.
A woman who only wanted to be referred to as Christine said she was rallying for pay equity for her colleagues.
"It's important to me that we're all paid the same for the job we do," she said.
"It's about everyone, it's not about me as an individual, it's about all of us."
The ralliers are chanting "union power" and "what do we want? Fair pay! When do we want it? Now!" while they blow whistles and bang sticks and flags on their signs.
Another woman said it was hard to put into words why the issue was important to her. She said she personally didn't feel disadvantaged, but many employees were being undervalued.
The group started marching to Asteron house at around 1.46pm.
They gathered under bus shelters waiting for speeches as a sudden downpour started falling.
Protesters stopped outside the MBIE building in Wellington and are crowding Stout St, making a racket with their sticks, signs, and whistles.