Section 139(5)

In my opinion, you cannot opt for a new tax regime by filing a revised return. Where no option has been exercised by the assessee to choose a new tax regime while filing the original return of income filed u/s 139(1) of the Act, it cannot be chosen by filing a revised return u/s 139(5)

In the case of salaried employees, they can switch from a new tax regime to an old tax regime or vice versa every financial year. But this option is allowed only once to a taxpayer who is having a business income. 

If a taxpayer opts for a new tax regime then he has to file Form 10IE with the dept. after the end of the FY and before the filing of ITR within the due date.