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GST Guides
Practical explainers on GST numbers, verification, classification codes and calculations — written for people who have to get a real transaction right.
Most GST questions come up at an awkward moment: a new supplier has sent an invoice, a GSTIN will not resolve, or nobody is sure whether a quote included tax. These guides are written for those moments — short enough to read while the question is live, detailed enough to actually answer it.
Start with the basics if you are new to GSTIN structure, go to verification if you are checking a supplier before paying, or jump to calculations if you are reconciling an invoice. Every guide ends with links to the tools on this site that do the same job automatically.
CheckYourGST is an independent service and is not affiliated with the Government of India or the official GST portal. These guides are general information, not tax advice.
Basics
What a GSTIN is, how it is built, and how GST registration works.
GST Registration Explained: Who Registers and What They Get
What GST registration is, who needs it, what the resulting registration record contains, and how that record shows up in a GSTIN lookup.
GSTIN Format Explained: What Each of the 15 Digits Means
A character-by-character walkthrough of the GSTIN format, with a generic example and the common mistakes that make a GST number invalid.
GSTIN vs GST Number: Is There Any Difference?
People use GSTIN and GST number interchangeably. Here is what each term strictly means and when the difference actually matters.
GSTIN vs PAN: How the Two Numbers Relate
PAN sits inside every GSTIN. This guide explains how the two identifiers connect, why one PAN can have many GSTINs, and what you can and cannot infer.
What Is a GSTIN? The 15-Character GST Number Explained
A GSTIN is the 15-character identity number issued to every GST-registered person in India. Here is what it is, what it encodes and how to read one.
Search
Finding a GST number, with and without the number itself.
GST Number Search by Company Name: What Is Actually Possible
Searching a GST number by business name has real limits. Here is how name search works, why results may be incomplete, and how to narrow down the right record.
How to Search a GST Number Online: A Practical Walkthrough
A step-by-step guide to searching a GST number, what each result field means, and how to handle the cases where nothing is found.
Verification
Checking a supplier, an invoice or a single GSTIN properly.
How to Verify GST Details on an Invoice
What a GST invoice must show, how to check each element against the supplier registration, and the mismatches that most often indicate a problem.
How to Verify a Supplier GSTIN Before You Pay
A practical supplier-verification routine for finance and procurement teams, including what to check at onboarding, at invoice stage and periodically.
How to Verify a GSTIN: The Full Verification Workflow
Verification is more than a lookup. This guide covers format validation, the live check, field-by-field comparison and what to do when something does not match.
Status
Reading Active, Cancelled and Suspended, and acting on each.
What Does a Suspended GSTIN Mean?
Suspension sits between active and cancelled. Here is what it usually signals, how it differs from cancellation, and how to handle a suspended supplier.
How to Check GST Registration Status
How to check whether a GST registration is active, what each status value means, and why a status is always a point-in-time answer.
What Does an Active GSTIN Mean?
An Active status confirms a live registration — and nothing else. Here is exactly what it covers, what it does not, and what to check alongside it.
What Does a Cancelled GSTIN Mean?
Why a GST registration gets cancelled, what it means for invoices already received, and what to do when a current supplier turns up cancelled.
GST Registration Date Explained: Why It Matters
The registration date is the most under-used field in a GSTIN lookup. Here is what it means and the checks it makes possible.
Classification
HSN and SAC codes, and how to pick the right one.
What Is an HSN Code?
HSN codes classify goods for tax and trade. This guide explains the structure, how to read a code from left to right, and where HSN appears in GST.
How to Find the Right HSN Code for a Product
A method for classifying a product properly: describe it precisely, work down the hierarchy, read the notes, and document the decision.
What Is a SAC Code?
SAC codes classify services under GST. This guide covers the structure, why they begin with 99, and how to pick the right one for what you actually supply.
HSN and SAC Codes Explained
HSN classifies goods, SAC classifies services, and both drive the GST rate on an invoice. Here is how the systems work and how they differ.
Calculations
Rate splits, adding and extracting GST, and inclusive pricing.
GST Inclusive vs GST Exclusive: What the Difference Costs You
The same number means two different prices depending on which basis is quoted. Here is how to tell, how to convert, and how to avoid the argument.
CGST, SGST and IGST Explained
One rate, three possible components. This guide explains which applies when, how to read the split on an invoice, and the errors it reveals.
How to Calculate GST: Formulas and Worked Examples
The two calculations you need — adding GST to a base price and extracting GST from an inclusive price — with worked examples and the mistakes to avoid.
Rates
How GST rates are set and where to confirm the current figure.
Reference
State codes and other lookup material.