Reverse GST, HST, PST & QST Calculator for Canada
Enter a total price to instantly see the amount before tax. Works for GST, HST, PST, and QST in every Canadian province and territory.
Extended precision is for auditing only. Do not paste 4-decimal values into standard invoicing software.
Calculations are arithmetic estimations only and do not constitute formal tax or corporate auditing advice. All figures must be verified against current CRA guidelines before filing.
✓ Rates verified
About TaxBackwards.ca
TaxBackwards.ca is a free Canadian reverse sales tax calculator built for bookkeepers, freelancers, sole proprietors, and small businesses. Enter a gross transaction total, select a province, and instantly extract the net pre-tax consideration and the claimable GST, HST, or QST amount.
All calculations use publicly available rates from the Canada Revenue Agency and Revenu Québec, manually verified and maintained. No accounts, logins, or user data storage — every calculation runs entirely in your browser.
TaxBackwards.ca is an arithmetic utility only and does not provide tax or accounting advice. Always verify figures against current CRA and Revenu Québec guidelines before filing.
Features
- Reverse GST/HST/QST calculations
- Auditor Precision Mode (4 decimals)
- Quebec French-Canadian formatting
- Copy-to-clipboard results
- Print-friendly ledger layout
Official Tax References
Canadian sales tax rules are administered by the Canada Revenue Agency (CRA) for federal GST/HST and by Revenu Québec for provincial QST. Businesses should verify all filings against official government guidance. TaxBackwards.ca uses publicly available published rates from both authorities.
Province & Territory Tax Guides
Detailed reverse sales tax guides are available for currently supported jurisdictions, covering formulas, worked examples, common amounts, and ITC eligibility rules.
Blog
Practical guides to Canadian reverse tax calculations.