More than 80,000 members of the Public and Commercial Services Union (PCS) who work for HM Revenue and Customs (HMRC) are banning overtime from Thursday, 1 March.
The union is participating in a national Civil Service-wide campaign against job cuts, privatisation and below-inflation pay rises.
HMRC plans to close down 200 processing sites with a total of 25,000 job losses by 2011.
The overtime ban will run until 5 April 2007 and follows a 24-hour strike across the Civil Service on 31 January and a subsequent two-week civil service wide overtime ban across England and Wales.
Mark Serwotka, PCS general secretary, said: “From strike action and work-to-rule, through to overtime bans, members have shown that they are resolute in standing up for the services they deliver.
“Such savage cuts in HMRC will undermine the ability of the department to function and serve only to damage services even further. Over the coming weeks further industrial action, including strike action, is highly likely if Civil Service managers and the government continue to bury their heads in the sand and fail to address the issues: job cuts, services and below inflation pay offers.”