Invoice Total & GST Calculator
Build a multi-line invoice with per-item GST, discounts and a correct total.
An invoice with three items at two GST rates, a discount on one line and TDS deducted by the customer is easy to get wrong by a few hundred rupees. This calculator builds the invoice line by line, applies discounts before tax, and produces the rate-wise tax summary your return needs.
Invoice lines
Result
Fill in the fields above and your result will appear here.
What the Invoice Total & GST Calculator does
Under GST, tax is computed per line on the taxable value after discount, then aggregated. Where several rates appear on one invoice, the summary must show taxable value and tax separately for each rate — which is why the tool groups them that way.
TDS adds a further wrinkle for service providers. The customer deducts it on the taxable value, not on the GST, so the amount you receive is lower than the invoice total while your GST liability is unchanged.
How to use this tool
- Add one row per item or service, with quantity and the rate excluding GST.
- Apply any discount per line as a percentage — it is deducted before tax is calculated.
- Set the GST rate for each line. Different lines can carry different rates.
- Add shipping or packing charges if you bill them, with the applicable rate.
- Enter the TDS percentage if your customer deducts tax at source, then read the net receivable figure.
Formula and method
Per line:
Gross = Quantity × Rate
Taxable = Gross − (Gross × Discount %)
GST = Taxable × GST rate
Invoice total = Σ Taxable + Σ GST (rounded to the nearest rupee)
TDS = Σ Taxable × TDS rate (on taxable value, not on GST)
Net receivable = Invoice total − TDS
Worked example
Example: three lines, two GST rates
| 2 × ₹1,500 at 18% | ₹3,000 + ₹540 |
| 1 × ₹4,000 less 10% at 18% | ₹3,600 + ₹648 |
| 5 × ₹250 at 12% | ₹1,250 + ₹150 |
| Taxable value | ₹7,850 |
| Total GST | ₹1,338 |
| Invoice total | ₹9,188 |
The rate-wise summary shows ₹6,600 taxable at 18% and ₹1,250 at 12% — the split your GSTR-1 requires.
What your result means
Taxable value is your revenue. It is what goes into your books and what margin is measured against.
Total GST is collected on behalf of the government and paid over in your return, net of input tax credit.
Net receivable is what actually lands in your bank account after the customer deducts TDS. The deducted amount is not lost — it appears in your Form 26AS and is credited against your income tax liability.
Important considerations
- A tax invoice must carry your GSTIN, the customer's GSTIN for B2B supply, an invoice number and date, HSN or SAC codes, and the place of supply. This tool computes amounts, not compliance.
- Discounts must be shown on the invoice and agreed at or before the time of supply to be deducted from taxable value.
- TDS rates for services depend on the nature of the payment. Confirm the applicable section before agreeing a rate with a customer.
- Where the recipient is a government body or a specified entity, TDS under GST may also apply in addition to income tax TDS.
- Round-off should be shown as a separate line on the invoice, which is standard practice in Indian accounting software.
Limitations of this tool
- It calculates amounts only. It does not generate a compliant tax invoice document, assign HSN or SAC codes, or file returns.
- Reverse charge, export invoices, e-invoicing requirements and composition scheme billing are not modelled.
- Only one TDS rate is applied to the whole invoice; mixed supplies attracting different TDS sections need separate calculation.
Frequently asked questions
Is GST calculated before or after discount?
After. Where the discount is shown on the invoice and was agreed at or before the time of supply, it reduces the taxable value and GST is charged on the reduced amount.
Is TDS deducted on the GST amount?
No. Income tax TDS is deducted on the taxable value excluding GST, provided the GST is shown separately on the invoice. Your customer still pays you the GST and you still remit it.
Can one invoice have multiple GST rates?
Yes, and it is common. Each line carries its own rate, and the invoice must show a rate-wise summary of taxable value and tax.
Is shipping taxable under GST?
When you charge it as part of a supply, yes — it generally attracts the rate of the principal supply as part of a composite supply. Where it is a separate service the treatment can differ.