About 4000 staff of Inland Revenue and the Ministry of Business, Innovation and Employment around the country will walk off the job for two hours on Monday in a bid for better pay.
"This isn't a decision our members have taken lightly but they feel they have no choice but to take industrial action," PSA national secretary Glenn Barclay said.
"We're asking for fair pay systems and a modest across-the-board pay increase but both employers have refused, and [Ministry of Business, Innovation sand Employment] even suggested staff work longer hours for the same pay.
"Public servants deserve better than this, and on Monday they will tell their employers that," Barclay said in a statement.
Comment was being sought from Inland Revenue and MBIE.
PSA members will strike between 1pm and 3pm. In Auckland they will block the central city intersection of Queen St and Victoria St for 40 minutes before marching to Freyberg Pl for a rally.
Police said they would be monitoring the activity but didn't anticipate any traffic issues in central Auckland.
Auckland Transport said it manage any situation live from ATOC Auckland Transport Operations Centre.
"We will manage traffic lights as needed and will use social media to keep the public up to date."
Marches and rallies will be held in other main centres including Wellington and Christchurch while in other towns and cities members have decided to do volunteer work.
Last month the Government announced that around 2000 of the lowest-paid public servants would move on to the 2018 living wage of at least $20.55 an hour.
The new hourly rate – or $42,744 a year – will cost an estimated $7.23 million for a one-off adjustment by September 1.
In subsequent years, the rate will be the subject of bargaining between employers and unions.
MBIE general manager human resources Richard Griffiths said: "We've got contingency plans in place and we're confident that any impact to customers and MBIE services will be minimal. For customers it should be business as usual.
"We remain committed to continuing constructive discussions with the PSA and reaching an agreement that's acceptable to both parties at the earliest possible opportunity."