<h1>Taxpayers Must Register Valid Email and Mobile on IT Dept's E-Filing Site for Secure Communication.</h1> Taxpayers are required to register or update a valid email ID and mobile number on the Income Tax Department's e-filing website to facilitate direct communication. The department will send separate One Time Passwords (OTPs) to both the registered email and mobile, which must be entered within 24 hours to authenticate the account. This measure addresses issues with incorrect contact details and aids in password resetting. A single email or mobile number can be linked to up to 10 user accounts as a primary contact, with additional secondary contacts allowed. Taxpayers are advised to whitelist department communications and maintain account security.