A GST registration number is a unique ID given to a business when it gets registered under the Goods and Services Tax (GST) system, and it is used by the government to track that businessā€™s GST-related activities like tax collection, invoice reporting, and return filing.

What is a GST registration number?

  • It is also called GSTIN (Goods and Services Tax Identification Number).
  • It is mandatory for businesses that cross the prescribed turnover limits or fall under compulsory registration categories (like eā€‘commerce sellers, interā€‘state suppliers, etc.).
  • It serves as the businessā€™s tax identity under GST, similar to how a PAN identifies you for income tax.

In simple terms: if you are legally allowed to collect GST on your sales, your proof of that is your GST registration number printed on your invoices and shown on the GST portal.

Structure: how many digits and what they mean?

For India, the GST registration number (GSTIN) has 15 characters in a fixed format.

A typical example: 27AAAPA1234A1Z5.

Breakā€‘up:

  • 1stā€“2nd characters: State code (e.g., 27 = Maharashtra, 08 = Rajasthan).
  • 3rdā€“12th characters: PAN of the business (10ā€‘character PAN).
  • 13th character: Entity/registration number under that PAN in that state (1, 2, 3ā€¦ if same PAN has multiple registrations).
  • 14th character: Usually ā€˜Zā€™ by default (reserved).
  • 15th character: Check code (alphanumeric) used for validation/error detection.

So, when someone asks ā€œwhat is GST registration number,ā€ they usually mean this 15ā€‘digit GSTIN that appears on GST invoices, registration certificates, and on the GST portal.

Purpose and importance

A GST registration number:

  • Proves that the business is legally registered under GST and can charge GST.
  • Is required to file GST returns and pay GST to the government.
  • Allows customers (especially other businesses) to claim input tax credit on the GST they pay you.
  • Helps tax authorities track supplies and prevent tax evasion.

Without a valid GST registration number where it is mandatory, a business can face penalties and cannot issue proper GST invoices.

Quick note: India vs. other countries

  • India : GST registration number is the 15ā€‘digit GSTIN with the structure explained above.
  • Singapore also uses the term ā€œGST Registration Number,ā€ but its format is a 10ā€‘character code issued by IRAS, separate from other IDs like UEN or NRIC.

So the exact format depends on the country, but the idea is the same: a GST registration number is the official tax ID for GSTā€‘registered businesses.

TL;DR: A GST registration number (GSTIN) is a unique tax ID issued to GSTā€‘registered businesses, typically a 15ā€‘character code in India, used on invoices and returns to identify and track GST compliance.

Information gathered from public forums or data available on the internet and portrayed here.