GST Number Format- Decode GST Number: Ultimate Guide 2025

Introduction

The GST number serves as an identifier for businesses in India. Understanding the GST number format helps companies and consumers verify entities and ensure compliance with tax regulations. Each GST number follows a structure that encodes vital information about the business. 

This blog breaks down the GST number format in simple terms, allowing you to confidently decode any GST identification number.

What is a GST Number?

A GST number, or Goods and Services Tax Identification Number (GSTIN), is a unique 15-digit code given to businesses registered under GST in India. The GST number format follows a standardized pattern that reveals details about the business entity. 

Since its implementation in 2017, the GST system has transformed India’s tax landscape, making the GST one of the most important business identifiers. 

By knowing how to verify a GST number format online, you can verify businesses, ensure compliance, and avoid potential fraud.

Importance of GST Number Format

Before diving into the GST number format details, let’s understand why it matters:

1. Legal Compliance: Having a valid GST number is mandatory for businesses with a turnover exceeding ₹20 lakhs (₹10 lakhs for special category states such as Mizoram, Tripura, Nagaland).
   
2. Business Credibility: A genuine GST number format proves your business’s legitimacy to customers and suppliers.
   
3. Tax Benefits: Input tax credits are only available for transactions between GST-registered entities.
   
4. Fraud Prevention: Knowing how to verify the GST number format helps avoid dealing with fake businesses.

Understanding the GST number format is crucial not only for verifying legitimate businesses but also for fraud prevention, helping you avoid engaging with fraudulent entities.

GST Number Format Explained

Every GST number format consists of 15 characters divided into specific segments. These segment reveals particular information about the business. 

Let’s decode the standard GST number format:

1. State Code (First 2 digits)

The first two digits of the GST number format represent the GST state code for the business that is registered. For example:

• 01: Jammu & Kashmir
• 07: Delhi
• 27: Maharashtra
• 29: Karnataka
• 33: Tamil Nadu

2. PAN Number (Next 10 characters)

The next 10 characters in the GST number format correspond to the Permanent Account Number (PAN) of the business entity. This includes:

• First 5 characters: Letters representing the PAN series
• Next 4 characters: Numbers in the PAN
• Last character: Alphabetic check digit

3. Entity Number (13th digit)

The 13th digit in the GST number format indicates the number of business registrations that the entity has within the same state. This is typically:

• 1 for the first registration
• 2 for the second registration, and so on

4. Check Digit (14th character)

The 14th character in the GST number format is an alphabetic check digit used for validation purposes.

The check digit is the last digit in a number sequence used to verify the accuracy of the entire number, ensuring it is valid.

5. Default Character (15th digit)

The last character in the GST number format is always ‘Z’, which serves as a default character.

GST Number Format Example

Let’s examine a GST number format example to better understand:

GST Number: 27AAPFU0939F1Z5

Breaking down this GST number format:

• State Code: 27 (Maharashtra)
• PAN: AAPFU0939F
• Entity Number: 1 (First registration in the state)
• Check Digit: Z
• Default Character: 5

Another format of GST number example would be 29ABCDE1234F1Z7, where:

• State Code: 29 (Karnataka)
• PAN: ABCDE1234F
• Entity Number: 1
• Check Digit: Z
• Default Character: 7

Common Types of GST Registration

Understanding different types helps in recognizing the purpose behind a specific GST number format:

1. Regular GST Registration: After GST registration, most businesses use a standard 15-digit GST number format: 2-digit state code, 10-digit PAN, 1 entity digit, “Z” as a default, and 1 checksum character.

2. Composition Scheme: Businesses under the composition scheme use the same GST number format but have different compliance requirements.

The Composition Scheme is a simplified GST tax scheme for small businesses with an annual turnover below a specified threshold, offering lower tax rates and fewer compliance requirements.

3. Non-Resident Taxable Person: Foreign entities doing business in India get a special GST number format.

4. TDS/TCS Deductors: Government departments deducting TDS have a unique format of GST number.

How To Verify GST Number Format

Verify a GST number by checking the state code, PAN connection, and using online tools like the RegisterKaro portal for validation.

The actual business name and address should match what’s registered for the GST number validation.

Dummy GST Number Format for Testing

For systems testing or training purposes, you might need a dummy GST number format. Remember that dummy GST number formats should never be used for actual transactions. A dummy GST number format typically follows the correct structure but doesn’t belong to any real entity.

Example of a dummy GST number format: 27AAAAA0000A1Z5

When using a dummy GST number format for testing, always ensure it’s marked as a test number to avoid confusion.

GST Number Format India Example: Special Cases

Some special cases in the GST number format in India include:

1. Government Departments

Government departments have a special GST number format where the fourth character is always ‘G’.

2. Public Sector Undertakings

PSUs follow the standard GST number format but can be identified through their registered names.

3. UN Bodies and Embassies

These organizations get a unique identification number (UIN) instead of the regular GST number format.

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Common Mistakes When Reading GST Number Format

People often make these mistakes when interpreting the GST number format:

1. Confusing the state code with different regions of the business.
2. Not recognizing that multiple registrations from the same PAN will have different entity numbers.
3. Assuming all 15 characters hold unique significance, the last character is always ‘Z’.
4. Mistaking similar-looking characters (0 vs O, 1 vs I) in the GST number format.

Conclusion

Understanding the GST number format is essential for businesses and consumers alike. The GST number format provides valuable information about the registered entity and helps maintain transparency in the tax system. 

Whether you’re a business owner verifying supplier credentials or a consumer checking business legitimacy, this knowledge about the GST number format empowers you to make informed decisions. Remember that a proper GST number format follows the 15-character structure with state code, PAN, entity number, and verification digits.

Are you ready to verify your next business transaction using your new knowledge of the GST number format? Take action today with RegisterKaro by checking the GST numbers on your recent invoices to ensure you’re dealing with legitimate businesses. Contact us today!

Frequently Asked Questions (FAQs)

1. What is a GSTIN?
A GSTIN (Goods and Services Tax Identification Number) is a 15-character alphanumeric code assigned to every GST-registered business in India.

2. How is the 15-character GSTIN structured?
• 2-digit state code → • 10-digit PAN → • 1-digit entity code → • default letter “Z” → • 1-digit alphanumeric checksum.

3. What do the first two digits indicate?
They represent the Census state code (e.g., 27 = Maharashtra, 09 = Uttar Pradesh).

4. Why does the GSTIN embed the PAN?
Linking the GSTIN to the taxpayer’s PAN ensures consistency between direct- and indirect-tax records and prevents duplication.

5. What is the purpose of the 13th character (entity code)?
It distinguishes multiple registrations tied to the same PAN within one state: “1” for the first branch, “2” for the second, and so on.

6. Does the 14th character ever vary?
No. The 14th character is always the filler letter “Z” and currently has no functional use.

7. How is the final checksum character generated?
The 15th character is an algorithm-generated alphanumeric checksum that validates the preceding 14 characters and detects data entry errors.