For AY 2024-25, NEW TAX REGIME is the default regime for Individual, HUF, AOP (other than co-operative society), BOI and Artificial Juridical Person.
If you want to opt for "OLD TAX REGIME" and you are
(i) Eligible to file return of income in ITR 1 & 2 , then select relevant option directly in ITR and file return within the applicable due date.
(ii) Eligible to file return of income in ITR 3, 4 & 5 then you MUST file Form 10-IEA to avail benefit of old tax regime, and file return within the applicable due date.
Please compare the tax liability under the New Tax and Old Tax regime before filing of the return. For computing tax liability please click on the link 'Income Tax Calculator'.