Communication Workers Union members at more than 100 Crown Post Offices will walk out on July 11. Larger branches often sited on high streets will close after workers rejected a three per cent rise and a £500 lump sum.
It will be the third strike by Post Office workers this year.
CWU boss Andy Furey said members “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”.