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IGST Calculator

IGST applies when the place of supply is in a different state or union territory, and on imports and exports. Enter the value and rate — you can add IGST to an exclusive amount or strip it out of an inclusive one.

The rate equals the full GST rate; there is no CGST/SGST split on an inter-state invoice.

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Common slabs are 0, 5 and 18, plus a 40% special rate for luxury and sin goods. Any custom rate works too.

IGST breakdown

Taxable valueIGST @ 18%
Taxable value
₹1,00,000.00
IGST @ 18%
₹18,000.00
Invoice total
₹1,18,000.00
IGST applies when the place of supply is in a different state or union territory.

This inter-state sale carries ₹18,000.00 IGST, collected in full by the Centre. Unlike an intra-state sale, there's no CGST/SGST split to work out.

Smart next steps

Formula

IGST = Taxable value × GST rate ÷ 100

Taxable value (from inclusive) = Inclusive amount ÷ (1 + rate ÷ 100)

Place of supply, not the transporter's route, decides whether GST is IGST or CGST + SGST.

Worked example

A Maharashtra business bills a Karnataka client ₹1,00,000 at 18%. IGST is ₹18,000 and the invoice total is ₹1,18,000.

How to use this calculator

  1. 1Enter the taxable value of the inter-state supply or export.
  2. 2Choose the GST rate applicable to the goods or services.
  3. 3Read the single IGST amount and the invoice total: there is no CGST/SGST split.

When businesses use it

  • Billing a customer in another state, where the full rate goes on one IGST line.
  • Pricing goods you ship across state borders through a courier or transporter.
  • Checking IGST on an import or an e-commerce sale delivered outside your state.

Inter-state supplies, imports and exports

IGST is a single levy at the full slab rate collected by the Centre and later apportioned to the consuming state. It applies whenever the supplier's location and the place of supply fall in different states or union territories, and also to imports, exports and supplies to or from special economic zones: categories the law treats as inter-state regardless of geography.

For e-commerce sellers this is the everyday case. A seller in Jaipur shipping to buyers across the country charges IGST on most orders, which keeps invoicing simple but makes the place-of-supply field on each order critical. For services, the default place of supply is the registered recipient's address, so a Bengaluru agency serving a Mumbai client bills IGST even though nothing physically moves.

IGST credit is the most flexible balance in the ledger: it can be used against IGST, then CGST, then SGST. Exporters who ship under payment of tax build up refundable IGST, while those using a Letter of Undertaking ship without tax and claim a refund of accumulated input credit instead.

Getting inter-state invoices right

  • Record the place of supply explicitly on every invoice, not just the billing address.
  • Never split IGST into two halves: the full slab goes on one line.
  • Choose between LUT and payment-of-tax exports before the first shipment of the year.
  • Watch bill-to/ship-to transactions, where the deemed place of supply is the third party's location.

Learn the maths behind it

  • GST 2.0: the new GST rates explained

    From 22 September 2025, GST runs on four slabs (0%, 5%, 18% and a 40% special rate) with most 12% items moving to 5% and most 28% items moving to 18%.

  • CGST vs SGST vs IGST

    Same-state sale: GST splits equally into CGST and SGST. Different-state sale: the whole rate goes on one IGST line.

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Frequently Asked Questions

IGST equals the total GST rate for the item — currently 5%, 18% or the 40% special rate — charged as a single line on the invoice.

Exports are zero-rated. You can export without payment of tax under a LUT, or pay IGST and claim a refund.

The Centre collects IGST and then apportions the state share to the state of consumption.

Yes. Imports attract IGST at the applicable slab on the assessable value plus customs duty, and the amount paid is available as input credit.

IGST credit must be exhausted first, against IGST liability, then against CGST and finally SGST.

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