# Flow of GST: How Each Chapter Fits Together
Understanding GST is easier when you see the decision flow that determines whether GST is payable, how much, and who pays it. Every chapter in the GST syllabus answers one specific question in this flow.
## Step 1: Is GST Payable At All?
Before computing any tax, you must answer three threshold questions in order:
Q1. Is the transaction a 'Supply'? (Chapter: Supply)
- If No → GST is NOT payable. Stop here.
- If Yes → proceed to Q2.
Q2. Is it an Exempt Supply? (Chapter: Exemptions)
- If Yes → GST is NOT payable. Stop here.
- If No → proceed to Q3.
Q3. Is the supply notified under Reverse Charge Mechanism (RCM)? (Chapter: Charge of GST)
- If Yes (RCM applies) → the Recipient is liable to pay GST (and is compulsorily required to register — see Registration).
- If No (Forward Charge) → the Supplier is liable to pay GST, provided he is registered or liable to register.
## Step 2: When, How Much, and Which Tax to Pay?
Once liability is established, three further questions arise:
| Question | Determined By | Chapter |
|---|---|---|
| When to pay GST? | Time of Supply rules | Time of Supply |
| How much to pay? | Value of Supply × Rate of Tax | Value of Supply (rate is fixed by Govt — not in syllabus) |
| Which tax to pay (CGST+SGST or IGST)? | Whether supply is inter-state or intra-state | Place of Supply |
Rule for which tax:
- Intra-State Supply → CGST + SGST/UTGST
- Inter-State Supply → IGST
## Step 3: GST Compliances
Compliances are grouped by frequency:
One-time:
- Registration (Chapter: Registration)
Continuous:
- Generation/issuance of documents like tax invoice, credit/debit notes, e-way bill (Chapters: Tax Invoice... ; E-Way Bill)
- Maintenance of Books of Account (Chapter: Accounts and Records)
Periodical:
- Deduction of TDS, if applicable (Chapter: Payment of Tax & TDS)
- Collection of TCS, if applicable (Chapter: Electronic Commerce)
- Filing of returns (Chapter: Returns)
- Payment of tax (Chapter: Payment of Tax)
## Step 4: How is the Tax Actually Paid?
GST liability is discharged from two sources:
1. Cash — through the Electronic Cash Ledger (Chapter: Payment of Tax)
2. Input Tax Credit (ITC) — using tax already paid at an earlier stage (Chapter: Input Tax Credit)
## Why this Flow Matters
In the exam, you will rarely be told which chapter a question belongs to. Mentally walking through this flow — Supply → Exemption → RCM → Time/Value/Place → Compliance/Payment — lets you identify which rules apply to a given fact pattern.