Post Office workers will walk out on 11 July in what will be the third strike this year in a dispute over pay.
Members of the Communication Workers Union (CWU) at more than 100 Crown Post Offices — the larger branches often sited on high streets — will walk out as workers strike against a real-terms pay cut.
The union said its members had rejected a pay offer it said was worth 3% with effect from April and a £500 lump sum, which the CWU said was well below inflation.
About 3,500 union members are involved in the dispute. The strike is expected to close all 114 Crown post offices.
It is the third bout of industrial action since the dispute flared and the union is not ruling out further strikes.
CWU assistant secretary Andy Furey said: “No worker wants to be in this situation, but Post Office bosses can’t be surprised that callous decisions are challenged by our members.
“This dispute is about dignity and respect for hard-working employees — essential public servants who, as key workers, provided unprecedented customer service during the pandemic.
“Our members feel betrayed and will not tolerate their living standards being smashed by people in charge of a public service that due to our members’ efforts made tens of millions of pounds in annual profits.
“There is more than enough money for a reasonable pay rise — implementing this pay cut is a management choice, not a necessity.”