Hundreds of staff at the Care Quality Commission were starting a work to rule today in a dispute over pay.
They include inspectors of health and social care organisations, workers in call centres and data analysts.
Their union Unison says employees will do only the minimum required under their contracts which includes only working the hours they are paid for, not doing overtime and taking all their breaks.
It follows a ballot last month in which 73% of more than 700 workers voted to strike and 92% said they would take action short of a total walkout.
The union was unhappy with a pay increase of between 2.75% and 3.5% received last December when employees also received one-off payments of £100 or £150.
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.’
A CQC spokesperson said: 'Four of our recognised Trade Unions, RCN, Prospect, UNITE and UNISON, have given notice that from Monday 17 April, their members will be taking action short of a strike (ASOS).
'We will remain in close contact with the unions as this develops.'