GSTIN is a 15 digit unique code which is assigned to each taxpayer, which will be State-wise and PAN-based. The first 2 digits of GSTIN can range from 01-35 and indicate the state code for the registration as per the Indian Census of 2011. The next 10 digits are the PAN number of the GST registered entity. The 13th digit of the GST Number is the entity code. The 14th digit for current GST registrations is “Z” by default. The last digit (15th) is currently used as a check code and may be a number or alphabet that has been assigned randomly.
The structure or format of 15 digit GSTIN:
|State Code||PAN||Number of Registration within State||Blank||Check Digit|
15th Digit in GSTIN is result of calculation applied on first 14 digits. The utility attached will help you to determine whether the GSTIN is valid or not.
Hope it is helpful.