GST Registration — Who Must Register and How

Learning Objectives

• Know the turnover thresholds that make GST registration mandatory
• Understand the different types of GST registration
• Identify every document needed for registration
• Walk through the GST portal registration process step by step
• Decode a GSTIN and understand what each part means

Who Must Register for GST?

GST registration is mandatory when your aggregate turnover crosses the prescribed threshold in a financial year.

Threshold Limits

Aggregate turnover = all taxable + exempt + zero-rated + non-GST supplies. It is calculated across all GST registrations of the same PAN, across all states.

Aggregate Turnover — Worked Example with Two GSTINs

Mr. Anil owns two retail businesses under the same PAN: a saree shop in Hyderabad (Telangana) and a tailoring outlet in Bangalore (Karnataka). The numbers for FY 25-26:

Aggregate turnover = ₹32,20,000.

Includes:

• All taxable supplies (intrastate + interstate)
• All exempt supplies
• All zero-rated supplies (exports + SEZ)
• All supplies under RCM (outward only — RCM inwards do NOT add)

Excludes:

• Inward supplies under RCM (already excluded above)
• The GST tax itself

Implications for Anil:

1. He is past the ₹20 Lakh services threshold AND past the ₹40 Lakh goods threshold's lower-services-mix limit. Registration is mandatory in both states.

2. Each GSTIN must independently file returns — Telangana GSTIN files GSTR-1/3B for Hyderabad activity, Karnataka GSTIN files for Bangalore. Aggregation only matters for threshold determination, not for return filing.

3. Even the Bangalore branch alone (₹12.2 Lakh) is mandatorily registered because of the PAN-level aggregate ₹32.2 Lakh.

4. If Anil opens a third branch in Chennai later, that turnover ALSO adds to the same aggregate.

This same computation determines Composition Scheme eligibility (₹1.5 Cr) and GSTR-9 applicability (₹2 Cr) — they all use aggregate turnover at PAN level.

Mandatory Registration — Regardless of Turnover

Some businesses must register even if turnover is below the limit:

• Interstate suppliers of goods
• E-commerce operators (and sellers on Amazon, Flipkart, etc.)
• Casual taxable persons
• Non-resident taxable persons
• Persons liable under Reverse Charge
• Input Service Distributors
• TDS/TCS deductors

Types of GST Registration

Casual Taxable Person & Non-Resident Taxable Person

Two special registration categories handle short-term and cross-border business — both require advance tax deposit.

Casual Taxable Person (CTP): Any person who occasionally supplies goods or services in a state where they have no fixed place of business. Common examples — a Hyderabad jeweller setting up a stall at a Chennai exhibition, a Mumbai consultant running a 3-day workshop in Bangalore, a Punjab textile trader at a Tirupur trade fair.

• Registration is valid for 90 days, extendable once by another 90 days (total 180)
• File Form GST REG-01 with "Casual Taxable Person" ticked
• Must deposit estimated tax in advance — calculated on projected sales for the period
• File GSTR-5 monthly during the validity period
• After 180 days max, the registration auto-expires

Non-Resident Taxable Person (NRTP): A foreign supplier (no fixed Indian establishment) making taxable supplies in India. Examples — a Hong Kong company exhibiting at a trade show in Delhi, a Dubai consultant providing training to an Indian client onsite.

• Registration is valid for 90 days, extendable by another 90 (total 180)
• PAN not required — instead, passport or other identity document
• Advance tax deposit on projected liability mandatory
• File GSTR-5 monthly (same form as CTP)
• Cannot opt for Composition

Both CTP and NRTP must register at least 5 days before commencing business. The 90-day validity window is strict — beyond it, separate fresh registration is required.

Benefits of Voluntary Registration

Even below the threshold, you may want to register voluntarily:

1. Claim ITC on your purchases — reduces your cost significantly
2. Supply to registered businesses — they need a tax invoice to claim ITC from you
3. Expand market — many B2B buyers prefer registered suppliers
4. Participate in government tenders — GST registration often required
5. Export — zero-rated exports require GST registration

Documents Required for GST Registration

For Sunrise Retail Pvt Ltd (Private Limited Company), DSC of at least one authorized director is mandatory.

Sunrise Retail — Case Study Application

💼 Sunrise Retail Pvt Ltd

Step 1 — Is registration mandatory?

Kiran Sharma projects year 1 turnover at ₹1.2 Crore. Sunrise Retail trades goods (electronics) from Telangana.

• Threshold for goods, regular state: ₹40 Lakh
• Projected turnover: ₹1,20,00,000 — exceeds threshold by 3× → Mandatory registration
• Additionally, they plan to sell to Bangalore → interstate supply → mandatory regardless of turnover

Step 2 — Documents prepared by Sneha Reddy (Finance Director):

Step 3 — GST Portal Registration Walkthrough

[GST portal landing page at www.gst.gov.in — Services → Registration → New Registration]

Part A — Basic Details:

Taxpayer Type: Regular
State: Telangana
District: Hyderabad
Legal Name of Business: Sunrise Retail Private Limited
PAN: AACCS1234A
Email Address: kiran@sunriseretail.in
Mobile: 9876543210

OTP sent to email and mobile. Enter both OTPs → TRN (Temporary Reference Number) generated.

[Screen showing TRN: 36-2025-XXXXXXXX — save this number to continue registration within 15 days]

Part B — Detailed Application:

Navigate to Services → Registration → New Registration → Continue with TRN

Tab 1: Business Details

Trade Name: Sunrise Retail
Constitution of Business: Private Limited Company
Date of Commencement: 01-April-2025
Reason for Registration: Turnover exceeds threshold

Tab 2: Promoters/Partners

Director 1: Kiran Sharma
  PAN: BBNKS4321Z | Aadhaar: 9876-XXXX-1234
  Designation: Managing Director | % Share: 50%

Director 2: Sneha Reddy
  PAN: CCCSR7654Y | Aadhaar: 8765-XXXX-5678
  Designation: Finance Director | % Share: 50%

Tab 3: Authorised Signatory

Kiran Sharma — Primary Authorised Signatory
Upload DSC → Select Class 3 DSC → Sign

Tab 4: Principal Place of Business

Address: Plot 45, Second Floor, Madhapur Main Road
State: Telangana | District: Hyderabad
PIN: 500081
Nature of Possession: Rented
Proof: Electricity bill uploaded (< 1MB)
Business Activities: Retail/Wholesale trade — Electronics
HSN Codes: 8517 (Mobile phones), 8471 (Laptops)

Tab 5: Goods and Services

Add Goods HSN:
  8517 — Telephone sets, smartphones
  8471 — Automatic data processing machines (laptops)
  8544 — Insulated wire, cables (accessories)

Tab 6: Bank Accounts

Bank: State Bank of India
Account Number: 38291047823
IFSC: SBIN0020229
Branch: Madhapur
Account Type: Current Account

Tab 7: Verification

Declaration: I hereby solemnly affirm...
Place: Hyderabad
Date: (auto-filled)
Sign with DSC of Kiran Sharma

Submit application → ARN (Application Reference Number) generated within minutes.

Processing Time: Typically 3–7 working days. Applicant receives GSTIN on email.

Decoding Sunrise Retail's GSTIN: 36AACCS1234A1ZP

A GSTIN is always 15 characters. Here is what each part means:

GSTIN Format Decoder

  3 6 A A C C S 1 2 3 4 A 1 Z P
  │ │ │ │ │ │ │ │ │ │ │ │ │ │ └─── Check digit (algorithmically derived)
  │ │ │ │ │ │ │ │ │ │ │ │ │ └───── Always 'Z' (reserved — has no meaning today)
  │ │ │ │ │ │ │ │ │ │ │ │ └─────── Entity number (1 = first registration in
  │ │ │ │ │ │ │ │ │ │ │ │           Telangana for this PAN; 2 = second; ...)
  │ │ └─┴─┴─┴─┴─┴─┴─┴─┴─┴────────── PAN of the business (10 chars)
  │ │                               AACCS1234A → standard PAN format:
  │ │                                 - 4th char 'C' = Company
  │ │                                 - chars 5–8 numeric, 9th alpha, 10th alpha
  └─┴───────────────────────────── State code (2 digits)
                                    36 = Telangana

Sunrise Retail GSTIN — 4-Line Breakdown

• 36 → Telangana state code. Every interstate invoice Sunrise issues carries IGST; every intrastate invoice carries CGST + Telangana SGST.
• AACCS1234A → Sunrise Retail's PAN. The 4th character C confirms the entity type is Company. Cross-checkable on the Income Tax portal.
• 1 → First GST registration in Telangana for this PAN. If Sunrise later opens a separate vertical under the same PAN in Telangana, that second GSTIN reads 2 at this position.
• ZP → Z is a reserved character (placeholder for future use). P is the check digit, derived algorithmically from the first 14 characters — used to instantly validate a typed GSTIN.

Why decoding matters in practice:

• Position 1–2 tells you instantly whether to apply CGST+SGST or IGST — no database lookup needed.
• Position 3–12 is the PAN — cross-verify against the supplier's invoice to catch fake invoices issued under spoofed GSTINs.
• Position 13 = "2" or higher hints at multiple registrations under the same PAN in the same state — common for vertical-split businesses, sometimes flagged in tax-planning reviews.

Full Position Table (Reference)

State Codes — Quick Reference (Common States):

GST Certificate — What It Contains

Once registered, the GST Certificate (Form GST REG-06) is issued. It includes:

• GSTIN
• Legal name and trade name
• Constitution of business
• Principal place of business address
• Additional places of business
• Date of liability to register
• Period of validity (annual for regular taxpayers — auto-renewed)
• The QR code (scan to verify on GST portal)

The GST certificate must be displayed prominently at all business places.

Amendment of GST Registration

If any registered details change, file Form GST REG-14 within 15 days of the change.

Core fields (require approval from officer):

• Name change, principal place of business change, addition of directors

Non-core fields (self-approved, effective immediately):

• Phone number, email, bank account, additional places, goods/services

Cancellation & Revocation — Preview

A registered taxpayer eventually exits — closure, transfer, retirement, scheme change, or simply not crossing the threshold any more. Knowing how to exit cleanly is as important as how to enter. The short version:

Voluntary cancellation (REG-16): five reason paths — change in PAN/constitution, ceased to be liable, business closure, transfer/merger, death of proprietor. The cancellation effective date determines when invoicing stops and triggers a stock-tax computation under Rule 44 — ITC originally claimed on stock and capital goods must be reversed on the cancellation date.

Suo-motu cancellation by officer (REG-17 → REG-19): triggered by 6 months non-filing (regular), 3 quarters non-filing (Composition), interstate sale by a Composition dealer, fraud, or non-payment of self-assessed liability. Often retrospectively dated — meaning past buyers also lose ITC under Section 16(2)(c).

Revocation (REG-21): if cancelled suo-motu by the officer, the taxpayer can apply for restoration within 30 days of the cancellation order, extendable up to 90 days. Conditions: all pending returns filed, all dues cleared.

Final return (GSTR-10): filed once, within 3 months of the cancellation order or effective date (whichever is later). Late fee capped at ₹10,000 but the most-forgotten compliance after cancellation.

Why this matters at registration time: the cancellation effective date you eventually pick (years from now) is bounded by the registration effective date you choose today. Get the start wrong and the exit is painful. Get the exit wrong and your stock-tax bill can wipe out a year's margins.

For the full mechanics — five reason paths, stock-tax computation including capital goods, REG-21 revocation procedure, suspension state, GSTR-10 final return — see Module 16 — Registration Cancellation & Revocation.

Practice Exercise

Exercise 1: A doctor (₹18 Lakh revenue) in Hyderabad also sells Ayurvedic medicines (₹8 Lakh). Is registration mandatory?

Exercise 2: TechWorld Mumbai (GST: 27AAACT5678B1ZX) sends an invoice to Sunrise Retail. Decode TechWorld's GSTIN.

Key Terms

Checklist — what you should now be able to do:

• Determine if registration is mandatory or voluntary for any given business
• Collect and organise all required documents before starting the portal application
• Decode any 15-character GSTIN and identify the state and entity number
• Walk through Parts A and B of the GST registration portal without help
• Advise a client on when to file REG-14 (amendment) vs REG-16 (cancellation)