The answer
₹1,180 inclusive of 18% GST
- Taxable value
- ₹1,000.00
- GST at 18%
- ₹180.00
- CGST at 9%
- ₹90.00
- SGST at 9%
- ₹90.00
- Invoice total
- ₹1,180.00
That split assumes the buyer is in your own state. For a buyer in another state the same ₹180 is charged once as IGST, with no CGST or SGST at all.
How it is worked out
GST amount = 1,180 − 1,000 = 180
CGST = SGST = 180 ÷ 2 = 90
₹1,180 at 18% is the textbook case because the numbers land cleanly: the base is exactly ₹1,000. That is precisely why it is worth memorising — if a ₹1,180 bill ever shows a taxable value that is not ₹1,000, either the rate is not 18% or someone has made an arithmetic error.
The mistake this example exists to prevent
Subtracting 18% from ₹1,180 gives ₹967.60. That is wrong by ₹32.40, and the error is structural rather than a rounding slip.
| Method | Result | Correct? |
|---|---|---|
| ₹1,180 − 18% | ₹967.60 | No |
| ₹1,180 ÷ 1.18 | ₹1,000.00 | Yes |
The 18% was applied to ₹1,000 to produce ₹180. Removing 18% of ₹1,180 removes ₹212.40 — more than was ever added. The formula behind the division explains why this holds at every rate.
What the invoice should say
Whatever you quoted the customer, a tax invoice cannot show ₹1,180 as a single inclusive line. The components have to appear separately, or your buyer cannot claim input tax credit.
| Line | Amount |
|---|---|
| Taxable value | ₹1,000.00 |
| CGST @ 9% | ₹90.00 |
| SGST @ 9% | ₹90.00 |
| Total invoice value | ₹1,180.00 |
Add your GSTIN, the buyer's GSTIN where they are registered, a serial invoice number, the date, the HSN or SAC code, and the place of supply. Those are the particulars that make it a tax invoice rather than a receipt.
₹1,180 at other rates
The same total means a different taxable value at every slab, which is why the rate has to be verified rather than assumed.
| Rate | Taxable value | GST | CGST / SGST each |
|---|---|---|---|
| 5% | ₹1,123.81 | ₹56.19 | ₹28.10 |
| 12% | ₹1,053.57 | ₹126.43 | ₹63.21 |
| 18% | ₹1,000.00 | ₹180.00 | ₹90.00 |
| 28% | ₹921.88 | ₹258.13 | ₹129.06 |
Most services — marketing, software, consulting, IT — sit at 18%. Check the SAC code for your specific supply rather than defaulting, because rates differ within categories more often than people expect.
Multiples of ₹1,180
Because ₹1,180 decomposes cleanly, its multiples do too, which makes them useful sanity checks against a spreadsheet.
| Inclusive total | Taxable value | GST |
|---|---|---|
| ₹1,180 | ₹1,000 | ₹180 |
| ₹5,900 | ₹5,000 | ₹900 |
| ₹11,800 | ₹10,000 | ₹1,800 |
| ₹59,000 | ₹50,000 | ₹9,000 |
| ₹1,18,000 | ₹1,00,000 | ₹18,000 |
Note
If your books show a taxable value against one of these totals that is not the round figure above, something upstream is wrong — usually a rate applied at 12% or a discount that was not recorded on the invoice.
Working forward instead
If you have the base and want the total, the calculation runs the other way and is simpler — multiply rather than divide.
GST = 1,000 × 0.18 = 180
Quoting ₹1,000 + GST and quoting ₹1,180 all-in describe the same transaction. Which you use depends on whether your buyer can reclaim the tax — a registered business can, a consumer cannot. The comparison covers when each is right.
What ₹1,180 means for your margin
If ₹1,180 is what you charged and ₹700 is what the work cost you, the profit is not ₹480. Only ₹1,000 of that total was ever your revenue.
₹1,180 charged, ₹700 cost
- Inclusive total
- ₹1,180.00
- Your actual revenue
- ₹1,000.00
- Cost
- ₹700.00
- Real profit
- ₹300.00
- Margin
- 30.00%
- Margin if you had used ₹1,180
- 40.68%
Ten percentage points of imaginary margin is enough to justify an advertising budget that loses money. Run both sides through the Profit Margin Calculator on tax-exclusive figures.
Common ways this figure goes wrong
- Subtracting instead of dividing, which gives ₹967.60 and a tax figure that will not reconcile.
- Splitting IGST in half. Inter-state supply carries one IGST line of ₹180, never ₹90 twice.
- Assuming 18% without checking. Verify the rate against the HSN or SAC code — at 12% the same ₹1,180 has a base of ₹1,053.57.
- Rounding the total before dividing, which pushes the error into the tax component your return reports.
The formula behind the division explains why the first of these fails at every rate, not just at 18%.
Frequently asked questions
What is the taxable value of ₹1,180 including 18% GST?
₹1,000. Divide ₹1,180 by 1.18. The remaining ₹180 is the GST, split as ₹90 CGST and ₹90 SGST for a same-state supply.
How much GST is in ₹1,180?
₹180 at the 18% rate. At 5% it would be ₹56.19, at 12% ₹126.43, and at 28% ₹258.13.
Is it ₹90 CGST and ₹90 SGST, or ₹180 IGST?
It depends on the place of supply. Same state means CGST and SGST of ₹90 each. Another state means a single IGST line of ₹180.
Can I show ₹1,180 as one line on the invoice?
No. A tax invoice must show taxable value and tax components separately. A single inclusive figure prevents your buyer from claiming input tax credit.