The Public and Commercial Services (PCS) union, which represents a number of staff in jobcentres, is to protest against the introduction of universal credit.
This new system, which combines a number of benefits into one monthly payment, managed online, has been introduced in Ashton-under-Lyne, Greater Manchester, today.
The PCS and staff at the Ashton-under-Lyne jobcentre are protesting at the government's 'demonising' of the unemployed and benefit claimants, believing it should prioritise job creation and support rather than universal credit.
The union believes the government's claim that some people on benefits are better off than those in work is untrue, and runs a campaign asking for proof of this.
PCS general secretary Mark Serwotka said: "If universal credit was being introduced to genuinely make life easier for people entitled to benefits it would be commendable, but the government's pernicious language exposes its real intent is to demonise and punish them.
"We have shown that ministers are prepared to mislead and misdirect to drive through their welfare cuts, so we are challenging Iain Duncan Smith and others to prove what they claim is true.
"The next time a minister says people are better off on benefits than in work, give them a pen and paper and ask them to show you how."
Minister for welfare reform Lord Freud said: "The start of universal credit today is a big step forward.
"We are finally implementing a benefit system that is fairer, where claimants will be better off in work than on benefits.
"We are introducing universal credit in a slow and safe manner so that we get this important reform right and help more people move smoothly from benefits and into work."