The CWU said that more than 115,000 of its members would take industrial action on Thursday 16 February, starting at 12.30pm, and running until the next day.
Union leadership said that Royal Mail had begun “forcing through unagreed changes related to the structure of work at offices across the country”, which it said contravened the agreed Industrial Relations Framework between employer and union.
Announcing the fresh strike dates, the CWU stated: “In effect, the changes represent the removal of the right of the CWU to negotiate at a local level, and must be viewed as a real step towards the derecognition of the union.”
CWU general secretary Dave Ward said the decision to strike again was down to the conduct of Royal Mail management, “who have displayed a complete lack of integrity”.
“Our members will not just sit back and watch as their working lives are destroyed by a company leadership hell-bent on ripping up historic arrangements that protect their rights and give them a voice through their union,” Ward said.
“It is postal workers who keep this company going and this country connected – it’s time management recognise this, drop the nasty games and begin taking negotiations seriously, so that this dispute can be ended for good.”
In its recent trading update, Royal Mail parent International Distributions Services said that the estimated net cost of the 18 days of strike action last year was around £200m.
Update: Royal Mail response.
A Royal Mail spokesperson said: “We entered facilitated talks through Acas in good faith, believing that the CWU were serious in their claim that they wanted a resolution. In announcing further damaging strike action, the CWU have shown they are not interested in resolving this dispute and continue to focus on damaging our business further.
“The CWU’s misguided belief that further industrial action will remove the need for change and force an improved offer, is misleading its members and risking their long-term job security. Their 18 days of industrial action have resulted in £200m losses in the year to date, cost our people around £1,800 in lost pay and inconvenienced our customers. We need to agree on changes to make our business more competitive. That is the only way to secure well-paid, long-term job security for our people.
“In a materially loss-making company, with every additional day of strike action, we are facing the difficult choice of whether we spend our money on pay and protecting jobs or on the cost of strikes. We remain committed to talks and urge CWU to withdraw these strikes for the good of our customers and our people.”