HP and EDS employees working on government IT contracts are voting on whether to take strike action after job and pay cuts.
The 1,000 workers with the Public and Commercial Services (PCS) union are mostly working on contracts with the Department for Work and Pensions around the UK.
The PCS union said there has been "growing anger" after HP took over EDS last year. On top of that, workers suffered pay cuts and faced 3,400 job cuts - with another 1,000 planned for the first half of next year.
PCS general secretary Mark Serwotka said: "Staff have been contributing significantly to HP's revenue, whilst shouldering greater workloads and helping to generate good profit levels."
"Yet their reward is more job cuts, imposed pay freezes and pleas from the company to take a voluntary pay cut," he added in a statement. "We will be urging members to deliver a strong yes vote and tell management that enough is enough."
HP said in a statement: "HP respects the rights of its employees to be part of a union. We will evaluate the situation as soon as the result of the local ballot is available. We will continue to maintain a dialogue with the union in an attempt to avoid any form of industrial action."
The vote runs until the end of the month.
Earlier this year, members of the Unite union also protested job cuts following the EDS/HP deal.
Fujitsu Services also faced a worker strike this month, but action is yet to be taken.
