---
url: /gst-manager-whmcs/guides/configure-gst.md
description: >-
  Enter your GSTIN and registered state, generate the IGST/CGST/SGST tax rules
  with the wizard or System Setup, and verify that WHMCS applies the right tax
  to every client.
---

# Set up GST correctly

Getting GST right comes down to one thing: WHMCS must charge **IGST** on inter-state sales
and **CGST + SGST** on sales within your own state. GST Manager sets this up for you once you
tell it who you are — your **GSTIN** (your 15-character GST registration number) and your
**registered state**. This guide walks you through it and shows you how to confirm it works.

::: info Why the client's state matters
GST splits by geography. When your client is in **another Indian state**, you charge a single
**IGST** (Integrated GST). When your client is in **your own state**, you charge two halves —
**CGST** (central) plus **SGST** (state). GST Manager generates both rule sets so WHMCS picks
the correct one automatically from each client's state.
:::

## 1. Enter your GSTIN and registered state

You can do this two ways:

* **During first-run setup** — on **Step 3, GSTIN & Tax Rules** of the
  [Setup Wizard](/gst-manager-whmcs/features/setup-wizard), enter your **15-character GSTIN**
  and pick your **registered state**. This is the only mandatory step in the wizard; an invalid
  GSTIN is flagged in red and you can't continue until it's valid.
* **Any time afterwards** — go to **Addons → GST Manager → System Setup → Tax & GST**, fill in
  the **Tax Type** and your **GSTIN**, and save.

![Entering GSTIN and registered state](/gst-manager-whmcs/img/gst-configure-gst-tax-and-gst.png)
*Addons → GST Manager → System Setup → Tax & GST*

## 2. Generate the IGST / CGST / SGST rules

From the same **Tax & GST** screen (or wizard Step 3), generate the tax rules. GST Manager
creates:

* **IGST 18%** — applied at the country level (India), for inter-state clients.
* **CGST 9% + SGST 9%** — applied for clients in your **registered state**.

::: tip One-Click System Setup
In a hurry? **System Setup** offers a **One-Click System Setup** that configures invoicing,
your GSTIN and the tax rules together in a single step — handy if you skipped parts of the
wizard.
:::

## 3. Verify the WHMCS tax configuration

The rules only fire correctly when each client's **state** is recorded, because the client's
state is what drives CGST/SGST vs IGST. To confirm everything is wired up:

1. Open a **test invoice** for a client in **your own state** — you should see **CGST 9%** and
   **SGST 9%** line items.
2. Open an invoice for a client in a **different Indian state** — you should see a single
   **IGST 18%** line item.
3. If a client shows **no tax**, check that their **state** is set on their profile and that
   the WHMCS prerequisites (per-line-item tax, taxable item types) are enabled — the wizard's
   **WHMCS Prerequisites** step fixes these with one button.

::: warning Client state is the switch
If a client's state is blank or wrong, WHMCS can't tell inter-state from intra-state and may
apply the wrong tax (or none). The **GST Compliance Health** widget on your dashboard flags
zero-tax domestic invoices so you can catch these quickly.
:::

## Related pages

* [Setup wizard](/gst-manager-whmcs/features/setup-wizard) — the guided 7-step first run
* [Settings reference](/gst-manager-whmcs/settings) — every System Setup field explained
* [GST Manager overview](/gst-manager-whmcs/)