After no movement from their bosses at Inland Revenue and the Ministry of Business, public servants will strike again on Monday.

More than 4000 employees walked off the job for two hours on July 9 but, since then, union delegates say "insufficient progress" has been made.

"We very much hoped we would not have to hold this second day of action, but our negotiations with MBIE and IR have made insufficient progress," PSA National Secretary Glenn Barclay said.

He said they were asking for fair pay systems and a modest across-the board pay increase.

"We're not asking the government for a handout, because we believe these two employers can afford it out of their existing baselines."

Rallies will be held across New Zealand, with some centres opting to hold community-based work for the period of the strike.

PSA National Secretary Erin Polaczuk said this is a last resort for union members.

"Our members are very reluctant to take strike action, because they know it will cause disruption.

"But they deserve better than this - and we're asking the employers to come back to the table ready to negotiate properly."

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.