The action is being carried out against Kerala-based jewellery group Joyalukkas and Manjali jewellers, I-T sources said.
"The searches are in progress," a senior official said tonight.
The raids began early morning at130 premises of the two business houses in the cities of Chennai, Hyderabad, Thrissur and other locations in Kerala, Karnataka, Andhra Pradesh, Telangana, Gujarat, Maharashtra, Delhi and West Bengal, the sources said.
The action, they said, is aimed at checking alleged tax evasion, following demonetisation, in the two firms.
Tax sleuths had allegedly detected huge cash deposits and sale figures of gold, diamond and jewellery in their accounts.
The Chennai wing of the department is coordinating the nation-wide action, involving over 100 tax sleuths and a number of police teams, sources said.