Online GST Calculator (Add and Remove GST)
Compute exact GST amounts for tax invoices. Supports Add GST (Exclusive), Remove GST (Inclusive / Reverse calculation), and automatic CGST, SGST, and IGST tax component breakdown.
GST Calculation Parameters
Tax Component Breakdown
| Central GST (CGST) | ₹ 9,000 |
| State / UT GST (SGST) | ₹ 9,000 |
| Integrated GST (IGST) | ₹ 0 |
| Gross Invoice Total | ₹ 1,18,000 |
Net Base = Gross / (1 + (Rate / 100)). For an 18% rate, divide gross by 1.18. The total GST amount is simply Gross - Net Base.
The Goods and Services Tax (GST) framework in India utilizes distinct algebraic equations depending on whether the invoice value is entered exclusive of taxes (forward computation) or inclusive of taxes (reverse extraction). Both methods are verified against the statutory guidelines issued by the Central Board of Indirect Taxes and Customs (CBIC).
1. Forward GST Calculation (Tax Exclusive)
Applied when goods or services are quoted at a net base price, and applicable taxes must be added to derive the final billed gross value.
Example: For an engineering consultancy order valued at a net base of ₹ 1,00,000 at 18% GST: Total GST = (1,00,000 × 18) / 100 = ₹ 18,000. Final invoice gross payable = ₹ 1,18,000.
2. Reverse GST Calculation (Tax Inclusive / Extraction)
Applied when receiving a total invoice amount that already includes indirect tax, requiring reverse decomposition into net value and tax liabilities.
Example: For a retail transaction of ₹ 1,18,000 inclusive of 18% tax: Net Base = 1,18,000 / 1.18 = ₹ 1,00,000. Extracted GST liability = 1,18,000 - 1,00,000 = ₹ 18,000.
India's multi-tier indirect taxation structure categorizes commodities and commercial services across five primary rate slabs. The applicable tax rate is governed by the Harmonized System of Nomenclature (HSN) for physical commodities and Services Accounting Codes (SAC) for professional, technical, and commercial services.
| Tax Slab | HSN / SAC Category | Representative Commodities & Services | Compliance & Treatment |
|---|---|---|---|
| 0% (Nil Rated) | HSN 01-21 (Basic Agri), SAC 9992/9993 | Unpackaged food grains, fresh vegetables, fresh milk, unbranded paneer, postal services, basic healthcare, and school education. | Zero output tax; entities cannot claim Input Tax Credit on fully exempt supplies. |
| 5% (Concessional) | HSN 10-15 (Processed), SAC 9964/9965 | Packaged pulses, spices, tea, life-saving oncology medicines, economy air tickets, railway AC freight, and goods transport agency (GTA) services. | Low margin merit goods; basic rate split into 2.5% CGST + 2.5% SGST. |
| 12% (Standard Lower) | HSN 30-38 (Pharma/Equip), SAC 9983 | Diagnostic reagents, surgical apparatus, business class air passenger travel, processed fruit juices, and state lottery procurement. | Intermediate industrial supplies and medical diagnostics; split 6% CGST + 6% SGST. |
| 18% (Standard Primary) | HSN 84-85 (Machinery), SAC 9954/9983 | Public works contracts, civil infrastructure, engineering consultancy, IT software, commercial leasing, banking, and capital machinery. | Primary rate applied to 70% of sovereign tenders and corporate services; split 9% CGST + 9% SGST. |
| 28% (Luxury & Demerit) | HSN 87 (Automotive), HSN 2523 (Cement) | Motor passenger vehicles, earthmoving machinery, cement, air conditioning units, and carbonated beverages (plus Compensation Cess). | Highest standard tier for non-essential luxuries; split 14% CGST + 14% SGST plus cess. |
Intra-State Supply (CGST + SGST / UTGST)
When the location of the supplier and the Place of Supply (POS) reside within the same Indian State or Union Territory with legislature, the statutory tax liability is split equally between the Central Government and the State Government:
- Central GST (CGST): 50% of total rate remitted to the Consolidated Fund of India.
- State GST (SGST): 50% of total rate remitted to the respective State Treasury.
- Union Territory GST (UTGST): Levied in lieu of SGST in Union Territories without a legislature (e.g., Ladakh, Andaman & Nicobar Islands, Chandigarh).
Inter-State Supply (Integrated GST / IGST)
When the location of the supplier and the Place of Supply reside across different States, across different Union Territories, or involve international import transactions, Integrated GST (IGST) is levied in full:
- Full Single Levy: 100% of the applicable GST rate is charged as IGST on the tax invoice.
- Inter-Government Settlement: IGST is collected by the Union Government and systematically apportioned to the consuming destination state.
- ITC Set-off Hierarchy: Under GST Rule 88A, accumulated IGST credit must be exhausted first before utilizing CGST and SGST balances.
Vendors, contractors, and service providers executing public sector contracts must factor in mandatory Tax Deducted at Source (TDS) under Section 51 of the Central Goods and Services Tax (CGST) Act, 2017. Governed by statutory notifications, the key compliance requirements include:
Deduction Exemptions: No TDS is deductible when the location of the supplier and the Place of Supply are in a State or Union Territory different from the State/UT of registration of the recipient authority. For civil contractors participating in GeM (Government e-Marketplace) and CPWD tenders, deducted amounts are reflected directly in the contractor's electronic cash ledger upon filing of Form GSTR-7 by the procuring department.
Under the 47th GST Council meeting recommendations, effective 18th July 2022 via Notification No. 03/2022-Central Tax (Rate), the concessional 12% GST rate on composite works contracts awarded by Central Governments, State Governments, local authorities, and governmental bodies was discontinued.
All such construction, erection, commissioning, installation, completion, fitting out, repair, and maintenance works contracts for public buildings, bridges, highways, and water supply infrastructure now attract a uniform 18% GST rate (SAC 9954). Bidders must verify whether tender bills of quantities (BOQ) request rates inclusive or exclusive of GST before finalizing financial bids.
How to calculate reverse GST from a total inclusive amount?
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