Challan Identification Number confirms payment realization and credit to government account, communicated to taxpayer and GSTN. A CIN (Challan Identification Number) is a 17 digit identifier (14 digit CPIN plus 3 digit bank code) generated when an authorized bank or the RBI receives and credits a payment to the relevant government account; it evidences payment realization and is communicated to the taxpayer and to the GSTN.