Police alleged the two employees fed secret, inside information to a consortium of two IT firms, IBM and Informatique EBR Inc., offering them an illegal edge over their competition.
IBM and EBR were vying with other companies for the contract to manage data for the Revenue Department.
The contract was never tendered.
All seven suspects face charges of fraud, conspiracy and breach of trust for acts that allegedly occurred between March 2011 and June 2014.
One of the Revenue Quebec employees is the brother of one of two EBR employees arrested.
Police said the suspects "acted in their own self-interest" and there was no evidence suggesting IBM or EBR were involved in the alleged scheme.
Treasury Board President Martin Coiteux said there are currently 38 ongoing IT contracts between the two suspected firms and the government.
He said all of them — 24 with IBM and 14 with EBR — will be reviewed.
"I asked the (government) to verify if any of the people implicated in (Wednesday's) arrests are tied any way to these contracts and, if they are, to send the information immediately to the anti-corruption unit," he said.
Two of the suspects were IBM employees and two worked for EBR. The other accused is a former Public Security Department employee.
Police said there they are still looking for an eighth suspect in the case — a third IBM employee — who is reportedly out of the country.
Revenue Quebec said in a news release the two employees charged in the case were suspended last summer when police began investigating.