Is gst length fixed

15 DIGIT NUMBER 

Here is a format break-down of the GSTIN:

• The first two digits represent the state code as per Indian Census 2011. Every state has a unique code.  For instance,
  • State code of Karnataka is 29
  • State code of Delhi is 07
• The next ten digits will be the PAN number of the taxpayer
• The thirteenth digit will be assigned based on the number of registration within a state
• The fourteenth digit will be Z by default
• The last digit will be for check code. It may be an alphabet or a number.