A GST-exclusive price shows tax separately and adds it to the taxable value. A GST-inclusive price already contains the tax, so the taxable value must be extracted from the final amount.
GST-exclusive calculation
When ₹1,000 is exclusive of 18% GST, calculate tax as ₹1,000 × 18 ÷ 100. GST is ₹180 and the final amount is ₹1,180.
GST amount
Taxable value × rate ÷ 100
Invoice total
Taxable value + GST amount
GST-inclusive calculation
When ₹1,180 already includes 18% GST, do not subtract 18% of ₹1,180. Instead divide ₹1,180 by 1.18. The taxable value is ₹1,000 and GST is ₹180.
Taxable value
Inclusive amount ÷ (1 + rate ÷ 100)
GST amount
Inclusive amount − taxable value
CGST and SGST versus IGST
For a typical intrastate supply, the total GST amount is divided equally between CGST and SGST. For a typical interstate supply, the total tax is generally shown as IGST. Place-of-supply and special-rule questions should be checked against current GST guidance.
| Example | Taxable value | GST | Total |
|---|---|---|---|
| 5% exclusive | ₹1,000 | ₹50 | ₹1,050 |
| 18% exclusive | ₹1,000 | ₹180 | ₹1,180 |
| 18% inclusive | ₹1,000 | ₹180 | ₹1,180 |
Sources and verification
Check current rates and notifications on the CBIC GST rate pages and updates published by the GST Council. This guide explains arithmetic and is not tax advice.