The PCS union has announced that its members will join other unions striking together in the autumn in the next mass strike to defend pensions.
Some 1,500 PCS members working for Atos Healthcare and Atos IT Services start balloting this week for strikes.
This follows votes by 95 percent and 89 percent respectively to reject below-inflation pay offers.
Workers at sites across Britain could strike during the Olympics, which lists Atos as a “worldwide partner”.
The health action could see assessment centres closed. The IT workers could hit tech support to the BBC, the Welsh Assembly and the Vehicle and Operator Services Agency.
PCS members in the Home Office are balloting on whether to strike.
They are challenging job cuts, attacks on pay, the imposition of a new performance management system, and the threat of privatisation and victimisation of union reps.
They believe the performance management will help bosses dismiss workers more easily. The ballot started on 4 July and is running for two weeks.
In HM Revenue and Customs, PCS members have began a work to rule. This is the continuation of a dispute that saw more than 55,000 tax workers strike last week against job cuts and privatisation.
A strike ballot in the Department for Work and Pensions was due to close on Wednesday of this week.
The dispute is over working conditions at 32 call centres and involves some 6,000 workers.
PCS members at the National Gallery in London are planning walkouts during the Olympics.