The agency says 250 people obtained the credits between 2009 and and 2012.
Police officers and government investigators searched 22 homes Wednesday evening, mostly in Quebec City and Trois-Rivières, as well as in Drummondville and Brossard.
There were daycares in 10 of the homes.
Stéphane Dion, a spokesperson for Revenue Quebec, said the investigation — called Project Bambino — began several weeks ago.
"For us it is a major investigation, because of both the number of people and the amount of money involved," Dion said.