Workers in hundreds of Crown Post Offices are set to stage their 12th round of industrial action since Easter.
Members of the Communication Workers Union in England, Wales, Northern Ireland and most of Scotland will walk out on Monday, followed by a strike in a handful of branches in Scotland on Tuesday.
Staff are also taking other forms of action including a sales ban on financial products and services.
The union is opposed to plans to franchise or close 75 Crown offices, the larger sites usually found on high streets.
More top news
The Chancellor will present his Autumn Statement and Spending Review to the House of Commons on Wednesday.
The shocking video of Laquan McDonald being killed brings the debate about racism in the US criminal justice system centre stage once more.
A video of a white police officer shooting dead a black teenager has been released by authorities in Chicago.