Set up a company and read a GSTIN
Every GST invoice starts with the seller: its legal name, address and GSTIN. In this lesson you learn to read a GSTIN, see who has to register, and set up the practice company you will use for the rest of the course.
What the 15 characters of a GSTIN mean
A GSTIN (Goods and Services Tax Identification Number) has 15 characters [GST portal, gst.gov.in]:
- Characters 1–2: the state code, for example 27 Maharashtra, 29 Karnataka, 07 Delhi, 24 Gujarat, 09 Uttar Pradesh.
- Characters 3–12: the PAN of the business.
- Character 13: the number of the registration for the same PAN in that state (1 for the first).
- Character 14: Z by default.
- Character 15: a check character worked out from the first 14. One mistyped character usually makes it fail, which is how software catches typing errors.
So 27ABCDE1234F1Z0 reads: Maharashtra, PAN ABCDE1234F, first registration. (This is a made-up sample with a correct check character, used in this course. It is not a real registration.)
Who has to register
A business must register once its aggregate turnover in a financial year crosses Rs 20 lakh (Rs 10 lakh in some special category states). States may allow Rs 40 lakh for businesses that supply only goods [CGST Act 2017, section 22; Notification 10/2019-Central Tax]. Some must register whatever their turnover, for example anyone making inter-state supplies of goods and sellers on e-commerce platforms [CGST Act 2017, section 24].
Why the company state matters
The state in your GSTIN decides which tax goes on each sale. A sale to a buyer in the same state carries CGST + SGST; a sale to another state carries IGST. You will see both in lessons 4 and 5, and Rebota picks the right one from the two state codes.
Practice task
Practice GSTIN (sample, not real):
Questions
Is the practice GSTIN real?
No. It is a sample built from the made-up PAN ABCDE1234F with a correct check character, so the software accepts it. Never put it on a real invoice.
Does the practice company cost anything?
No. The course and the practice company are free. The practice company is marked PRACTICE, is left out of Rebota's counts of businesses and sign-ups, and you can remove it in one click. While it exists it is one of your companies, so it can use a company slot on your plan; removing it frees the slot.
Reviewed: 7 Nov 2026. This is general information, not advice from a chartered accountant. Rates and rules change; check the source named in brackets.