Sheriffs, whose duties include security and enforcing court orders, will stop working for two hours on Thursday morning as they call for better pay and more staff.
They say their duties have increased significantly in the past decade but their pay has not reflected that.
That has made recruitment a tough ask, along with retaining the staff who feel they are facing the extra pressure at work.
Public Service Association general secretary Stewart Little claimed a review of the sheriffs' pay was completed last year, but never released because of cabinet confidentiality.
He said a lack of action put the workforce in a position where they have "had enough".
"Sheriffs waited patiently and were told the matter would be resolved in the 2024 budget, but when it was delivered in mid-June nothing happened and now they've been fobbed off again with some other made up bureaucratic process," Mr Little said.
"They need a solid pay bump to reflect the dangerous work they do, when enforcing court orders they'll be entering people's properties wearing stab proof vests, carrying capsicum spray, batons and handcuffs."
A Communities and Justice department spokesman said the sheriffs had been offered a 10.5 per cent pay rise over three years, in line with the government's public sector wage offer in May.
The spokesman said "good-faith negotiations" would continue.
"The two-hour stop work means courthouses in that area may need to delay opening, potentially up to a few hours later than the normal time of 9am," the spokesman told AAP.
"The sheriff's office has contingency plans in place to reduce any impacts on courts, where possible."
A quarter of the state's 170 courthouses will be affected by Thursday's protest, although no Sydney-based courts will be impacted.
The Public Service Association said the protest would have a "severe impact" on the courts' ability to function.
Sheriffs are also responsible for the security of judges, magistrates and lawyers.
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