Thousands of HM Revenue and Customs workers are to stage demonstrations in protest at the Government's public sector pay cap.
Members of the Public and Commercial Services (PCS) union will hold rallies across the country today to mark the imposition of another year of a below-inflation rise.
Wages in the civil service have fallen by around 12% in real terms during the past decade, coinciding with a programme of office closures, the PCS said.
General Secretary Mark Serwotka said: "Members are angry at another year of a pay cut in real terms. With inflation well above the Government pay cap this puts more of our members in poverty.
"The Government should be rewarding hard working staff not making them suffer. This is the first in a series of protests from PCS members and we will be working with other TUC unions to challenge the Government's public sector pay cap in the autumn."
The Government has come under pressure to ease the pay restraint which has seen public sector workers subjected to a 1% cap on wage rises since 2012, following a two-year freeze.
Despite this, the Government announced teachers' pay will remain capped earlier this month.
Last week, members of the Royal College of Nursing staged around 40 events across the UK on Thursday as nurses stepped up their campaign against the pay cap.