GST/QST Calculator (Canada)
Calculate GST and QST on a base amount or split from a total
Illustrative computation; tax regimes vary. Verify current CRA/Revenu Québec rules.
How to Use This Calculator
Enter amount and rates
Provide the monetary amount, GST, and QST rates.
Choose inclusive or exclusive
If inclusive, the amount already contains GST+QST; otherwise GST and QST are added.
Calculate
See base, GST, QST, and the grand total.
Formula
Exclusive: GST = base×g; QST = (base+GST)×q; Total = base+GST+QST. Inclusive: base = total/[(1+g)(1+q)].
About GST/QST Calculator (Canada)
This GST/QST Calculator illustrates how federal GST and Québec’s QST combine on purchases. Québec generally applies QST to the GST-inclusive amount, which this calculator models for clarity. Because Canadian sales tax rules include exemptions, zero-rated items, registration thresholds, and filing details, treat this tool as an arithmetic helper rather than compliance guidance. Always verify current rates and rules with CRA and Revenu Québec.
Frequently Asked Questions
Is QST calculated on top of GST?
Often, yes—QST is applied on the GST-inclusive base in Québec.
Are rates fixed?
Rates can change. Always confirm current GST and QST rates.
Does this handle input tax credits?
No. This tool focuses on invoice math, not filing and credits.