Financial Planning3 min read•Updated 2026-09-04
Reverse GST Calculator Formula: How to Extract Tax from Total Price
Calculate the exact original price before GST or VAT from any tax-inclusive invoice or store receipt.
MX
MultiToolX Financial Team
Tax & Accounting
Key Takeaways
- Reverse Tax Formula: Original Price = Total Price / (1 + Tax Rate / 100).
- Tax Paid = Total Price - Original Price.
- Essential for accounting reconciliations, expense reports, and input tax credit (ITC) claims.
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1. Step-by-Step Reverse GST Example
If you paid $590 for electronics with 18% GST included:
- Original Price = 590 / (1 + 0.18) = 590 / 1.18 = $500.00.
- GST Paid = 590 - 500 = $90.00.
Frequently Asked Questions
Why does multiplying the total by the tax rate give the wrong answer?
Because multiplying the final price calculates tax on top of the tax itself. The tax was originally assessed against the lower base price.
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