finance ToolUpdated 2026-09-21
Reverse Tax Calculator (Extract Pre-Tax & VAT)
When invoices or receipts display only the gross final total, this reverse tax calculator works backwards to deduce the exact pre-tax price and statutory sales tax, VAT, or GST share.
Frequently Asked Questions
Why can’t you simply subtract 15% from the gross amount?
Because sales tax is calculated as a percentage of the lower pre-tax base. Subtracting 15% from $115 gives $97.75, which is mathematically incorrect.
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