GSTIN Validator with checksum validation.
What is GSTIN..?
GSTIN refers to GST Identification Number assigned to every GST registered dealer in India.
Format/Pattern of GSTIN
GSTIN is a 15 digit unique code which is PAN-based. The structure or format of 15 digit GSTIN will look like below.
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Digits 1 & 2 : State Codes - the state code in the GST registration number represent the following states: Refer Here
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Digits 3 – 12 : PAN - represent the PAN of the entity, so that there is a connection between the GST and the PAN database.
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Digit 13 : Entity Code - this is alpha-numeric (1-9 and then A-Z) and is assigned based on the number of registrations a legal entity (having the same PAN) has within one State
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Digit 14 : Static Z
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Digit 15 : Checksum - Check Digit obtained from 'luhn mod 36'
Validating GSTIN in .NET
Example/Demo Application