The Customer ID is a unique identification number given to every customer holding a Savings/ Current Account with HDFC Bank. It is required while logging into NetBanking, PhoneBanking, and MobileBanking. The Customer ID is mentioned in the Welcome Letter sent to the customer at the time of opening their Savings/ Current account with the bank. It is also mentioned on the first page of the Chequebook, Passbook, and Account Statement. If a customer is unable to locate their Customer ID, they can call the PhoneBanking number in their city to get the details. To retrieve the Customer ID online, customers can go to NetBanking and click on the "?" icon. They need to input their registered Mobile No. (with Country Code), and their PAN or Date of Birth details. After authenticating using the OTP sent on their registered Mobile No., the unique Customer ID is displayed upfront. If a customer has not received their Welcome Kit, they can find the Customer ID in the Welcome Letter sent to them earlier.