More than 100,000 civil servants are going on strike on Prinsjesdag in an escalation of a dispute over wages, pensions and job security.
The Public and Commercial Services (PCS) union has announced a new strike date of March 15, when Chancellor Jeremy Hunt will unveil his spring budget.
It follows a strike last week in which hundreds of thousands of members of 123 government departments in England, Scotland and Wales walked out.
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The union warned next month’s strike could include a further 33,000 members working for 10 other employers, including HM Revenue and Customs (HMRC), whose vote results are due on February 28.
PCS general secretary Mark Serwotka said: “Rishi Sunak doesn’t seem to understand that the more he ignores our members’ demands for a pay rise to help them through the cost of living crisis, the angrier and more determined he makes them. .
“PCS members are suffering a wholly unacceptable drop in their pay. In April, for example, a third of HMRC staff will be earning just below minimum wage. 40,000 civil servants have taken advantage of a food bank. It is an appalling way for the government to workforce.”
Serwotka said the prime minister “can end this dispute tomorrow if he puts more money on the table”.
He warned: “If he refuses, more action is inevitable.”
The PCS union is calling for a 10% wage increase, protection of pensions and protection against job losses.
The government has said the demands – which it says would cost £2.4bn – are prohibitively expensive.
The dispute is becoming increasingly bitter as Mr Serwotka arranged talks last month to prevent the action a “complete farce” and warning of future strikes “becomes even bigger” if the ministers do nothing.
The strikes have affected several key government departments and agencies, including Border Force, National Highways, the Department for Work and Pensions and the Driver and Vehicle Licensing Agency (DVLA).
The new members being elected include those working for HMRC, the Welsh Government, the Care Quality Commission and Companies House.
Civil servants are among the thousands of public sector workers who have gone on strike because of rising inflation and declining living standards.
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Nurses continued their union action today after walking out with paramedics and call handlers on Monday in what was the largest strike in NHS history.
Environmental Agency workers will leave tomorrow, while teachers and university staff will continue to strike next week.
Union leaders have pleaded with the government to take action to prevent further strike action, but ministers in England have indicated they will not budge on one of the main points of contention: pay for 2022/23.