Reverse GST calculator

What is reverse GST?

Reverse GST is the arithmetic of pulling the tax back out of a price that already includes it. When a receipt or an MRP shows a single GST-inclusive figure, this calculator finds the base price and the GST contained in it: the base equals the total divided by one plus the rate, so 1,180 rupees at 18 percent comes from a 1,000 base plus 180 GST. It also shows the split every Indian invoice records, CGST and SGST at half the rate each within a state, or a single IGST at the full rate across states. Enter the inclusive total, choose the rate, and read back the base and the tax. Use it to reconcile an inclusive quote, to raise a correct invoice, or to check the GST already paid on a purchase.

Key facts

• A reverse GST calculation starts from a GST-inclusive price and finds both the original base price and the tax it already contains.
• The reverse GST formula is base equals total divided by (1 plus rate/100), and GST equals total minus base.
• A 1,180 inclusive amount at 18 percent works back to a 1,000 base and 180 GST, and a 1,050 amount at 5 percent gives a 1,000 base and 50 GST.
• The extracted GST splits into CGST and SGST at half the rate each for an intra-state supply, or a single IGST line for an inter-state supply.
• A reverse GST calculation is used when a quoted or MRP price is GST-inclusive and the pre-tax value is needed for accounting or input-tax-credit records.

Glossary

Reverse GST calculation

A reverse GST calculation starts from a GST-inclusive price and finds both the original base price and the tax already contained in it. It is the opposite of adding GST on top of a base amount.

GST-inclusive amount

A GST-inclusive amount is a price that already contains the tax, such as an MRP or a quote marked inclusive. The pre-tax base is often needed from it for accounting or input-tax-credit records.

Reverse GST formula

The reverse formula is base = total / (1 + rate / 100), and GST = total minus base. A 1,180 inclusive amount at 18 percent gives a 1,000 base and 180 GST.

CGST / SGST / IGST split

The extracted GST is split into CGST and SGST at half the rate each for an intra-state supply, or shown as a single IGST line at the full rate for an inter-state supply, matching the invoice.

Input tax credit (ITC)

Input tax credit lets a registered business offset the GST it paid on purchases against the GST it collects on sales. Extracting the tax from an inclusive price gives the figure recorded for ITC.