Hundreds of staff at the Care Quality Commission (CQC) are to work to rule from next week in a dispute over pay.
Unison said those taking industrial action from Monday include inspectors of health and social care organisations, workers in call centres and data analysts.
The action will involve employees doing no more than the minimum required under their job contracts, such as working only the hours they are paid for, not doing overtime and taking all the breaks to which they are entitled.
The union has criticised a pay increase of between 2.75% and 3.5%, received last December.
Employees also received a one-off payment of £100 or £150 depending on their salary grade.
CQC staff regulate health and social care services across England including hospitals, care homes, GP practices and dental surgeries to ensure care is delivered safely.
Unison national officer Matthew Egan said: “The fact so many CQC staff voted for action speaks volumes. They’re woefully underpaid and undervalued, and deserve much better.
“For a decade, they’ve seen their wages falling behind inflation. Now the cost-of-living crisis is leaving many struggling.
“CQC workers do a vital job to make sure safe care is delivered. This needs to be recognised by the government with a fair pay increase.”