Is it necessary for the employee to intimate the tax regime to the employer?

Tax regime intimation: employees must notify employer for payroll withholding; formal regime election must be made with the return.

An employee must intimate the employer about the intended tax regime during the year; if no intimation is given, the employer may treat the employee as in the default new tax regime and deduct tax accordingly. That employer-directed intimation does not constitute the formal exercise of the option to opt out of the new regime, which the employee must separately make when filing the income tax return by the statutory due date.