CRN stands for Challan Reference Number, which is a unique identification number generated by the Income Tax Department when a taxpayer generates a challan form to make a tax payment. The CRN is used to track the status of the payment and to ensure that the payment is credited to the correct taxpayers account. The Generate Challan Form (CRN) service is available to all users on the e-Filing portal, and it allows taxpayers to generate a Challan Form (CRN) and subsequently make a tax payment through selected authorized banks. The CRN is generated after the taxpayer enters their PAN/TAN and mobile number, and it must be used to make the tax payment within 15 days from the date of CRN generation. The status of the payment can be checked using the CRN, valid PAN/TAN, and an active mobile number.