A rally will be held outside the Senedd today following the Chancellor George Osborne's spending review announcement yesterday.
Cardiff Trades Council will be supporting the PCS union in protest to continued job and spending cuts.
Steve Ryan is the branch secretary for the PCS North Wales Revenue and Customs. He says today's strike is about pay and pensions.
PCS union rep Steve Ryan said that early estimates are that up to 90 percent of staff in Wrexham have joined the one day strike.
Speaking to reporter Ian Lang at the picket line at Wrexham tax office he said: "This is about protecting public services and jobs. We believe there is a fairer alternative to austerity."
Union members are protesting as part of a long-running dispute with the UK Government over pay and pensions, with thousands of public sector workers staging a 24-hour strike today.
Members of Britain's largest civil service union will strike today over pay and pensions.
The Public and Commercial Services Union (PCS) announced the strike after a ballot at the start of March.
Sites affected include job centres, tax offices and benefits offices, DVLA branches and some museums and galleries.
The union says its members want to "stop attacks on their livelihoods and job security".