Invoice Calculator - Calculate GST Invoice Amount & Tax Breakup
Generate professional invoice totals with CGST, SGST, IGST splits, trade discounts, shipping charges, and client TDS deductions.
Calculation Summary
Invoice & Tax Breakup Visualizations
Mastering GST Invoicing & Compliance for Indian Enterprises
Issuing compliant, transparent commercial tax invoices is a cornerstone of operational finance for Indian MSMEs, service providers, and B2B traders. Under India's Goods and Services Tax (GST) framework, an invoice is not merely a payment request—it serves as the essential statutory voucher enabling recipient buyers to claim Input Tax Credit (ITC) under Section 16 of the CGST Act. Calculating tax rates incorrectly or failing to bifurcate intra-state versus inter-state supply levies can lead to invoice rejections, blocked buyer credits, and cash-flow bottlenecks.
A compliant Indian invoice precisely maps gross item subtotals, records pre-tax trade discounts, applies appropriate GST statutory slabs (0%, 5%, 12%, 18%, or 28%), appends freight or insurance surcharges, and computes any applicable withholding tax (TDS under Section 194C, 194J, or Section 194Q). Mastering these calculations ensures billing accuracy, simplifies monthly GSTR-1 and GSTR-3B filings, and protects enterprise liquidity against GST audit notices.
Statutory Invoice Calculation Formulas
1. Net Taxable Supply Value
Gross subtotal less trade discounts granted on invoice face:
Taxable Value = Gross Subtotal - Trade Discount
Under Section 15(3) of CGST Act, post-supply cash rebates cannot be deducted unless pre-agreed.
2. Intra-State Tax Split (CGST + SGST)
When supplier and recipient are in the same state:
CGST = Taxable Value × (Rate / 2) | SGST = Taxable Value × (Rate / 2)
For an 18% slab: 9% CGST goes to Central Govt; 9% SGST to State Govt.
3. Inter-State Tax (IGST)
When supply crosses state or union territory boundaries:
IGST = Taxable Value × Rate
Full tax is collected as Integrated GST under the IGST Act.
4. Grand Total & Net Remittance Due
Total amount payable after freight and income tax withholding:
Grand Total = Taxable Value + Total GST + Shipping - Client TDS
Corporate clients deduct TDS (e.g. 2% under Sec 194J) on taxable base only.
Illustrative Invoice Tax Scenarios (On ₹1,00,000 Base)
Comparison showing how different GST slabs, interstate movement, and TDS deductions impact invoice totals:
| Billing Scenario | Taxable Value (₹) | GST Rate | CGST + SGST (₹) | IGST (₹) | TDS Deduction (₹) | Total Payable (₹) |
|---|---|---|---|---|---|---|
| Intra-State IT Services (18%) | ₹1,00,000 | 18% | ₹9,000 + ₹9,000 | - | ₹2,000 (2% 194J) | ₹1,16,000 |
| Inter-State Consulting (18%) | ₹1,00,000 | 18% | - | ₹18,000 | ₹2,000 (2% 194J) | ₹1,16,000 |
| Wholesale Goods (12% Intra) | ₹1,00,000 | 12% | ₹6,000 + ₹6,000 | - | ₹100 (0.1% 194Q) | ₹1,11,900 |
| Essential Commodities (5% Intra) | ₹1,00,000 | 5% | ₹2,500 + ₹2,500 | - | - | ₹1,05,000 |
| With 10% Trade Discount (18% Inter) | ₹90,000 | 18% | - | ₹16,200 | ₹1,800 (2% 194J) | ₹1,04,400 |
As the scenario comparison demonstrates, trade discounts reduce the taxable supply base, generating direct tax savings for the buyer without reducing the supplier's proportional margin efficiency. When billing corporate clients, ensure you clarify whether client TDS will be deducted under Section 194C (contractors), Section 194J (technical services), or Section 194Q (purchase of goods exceeding ₹50 Lakh). Note that TDS must strictly be calculated on the net taxable amount, excluding the GST portion, as mandated by CBDT Circular No. 23/2017.
In conclusion, adhering to Rule 46 invoice particulars—including 6-digit HSN codes for goods or SAC codes for services—ensures seamless matching in buyer GSTR-2B statements and prevents reconciliation disputes. Use the live calculator and CSV export tool above to create error-free invoice breakdowns, model interstate tax splits, and accelerate client payment clearances.
Frequently Asked Questions
What mandatory fields must appear on a GST Tax Invoice under Rule 46?
Under Rule 46 of CGST Rules, a valid tax invoice must include: Supplier Name, Address and GSTIN; consecutive serial number; date of issue; recipient Name, Address and GSTIN (if registered); HSN/SAC code; description of goods/services; quantity; taxable value; applicable GST rate (split into CGST/SGST or IGST); and signature of supplier.
How is GST determined between Intra-State and Inter-State sales?
When the location of the supplier and the place of supply are in the same Indian state or union territory (Intra-State), GST is equally divided between Central GST (CGST) and State GST (SGST/UTGST). When supplier and place of supply are in different states (Inter-State), Integrated GST (IGST) applies at the full rate.
Is GST calculated before or after trade discounts?
Under Section 15 of the CGST Act, trade discounts given before or at the time of supply that are recorded on the invoice face are deducted before calculating GST. Tax is charged only on the net taxable amount.
Who is required to issue e-Invoices in India in 2026?
Businesses with an aggregate annual turnover exceeding ₹5 Crore in any preceding financial year since FY 2017-18 are mandated to generate electronic invoices (e-Invoices) with an Invoice Reference Number (IRN) and QR code via the GST portal for B2B transactions.