11/04/2023
Do this asap!
All employees who want to choose the old regime MUST tell their employer by the end of this month, before your employer deducts TDS on the first salary slip of the new financial year. In the absence of a specific choice, the default is new regime. This can mean higher TDS than you would otherwise pay, assuming you are claiming several deductions like 80C, HRA, home loan interest, medical insurance etc.
2) If you don't file your return by the due data (generally 31st July), you are defaulted in the new regime. Even if you've made tax-saving investments on time, they will be of no use. That money will go to waste.