Implement GST/HST and provincial sales taxes

[MaxGhenis]

Summary

• Implements Goods and Services Tax (GST) / Harmonized Sales Tax (HST)
• Implements Provincial Sales Tax (PST/QST)
• Part of achieving SPSD/M parity (Implement Spouse's Allowance Benefits #517, Implement commodity taxes (liquor, tobacco, gasoline) #518)

Changes

Parameters Added

• GST/HST rates for all provinces (5% federal, up to 15% harmonized)
• Provincial sales tax rates (BC 7%, MB 7%, QC 9.975%, SK 6%)

Variables Added

• consumption: Household consumption spending subject to sales tax
• gst_hst: GST/HST paid on consumption
• provincial_sales_tax: PST/QST paid on consumption
• total_sales_tax: Total sales tax (GST/HST + PST)

Test Coverage

• GST/HST tests for 6 provinces
• PST tests for provinces with separate sales tax
• Total sales tax integration tests

Implementation Notes

• HST provinces (ON, NB, NS, NL, PE) have combined federal-provincial tax
• GST+PST provinces (BC, MB, SK) have separate taxes
• Quebec has GST + QST (Quebec Sales Tax)
• Alberta, NWT, NU, YT have GST only (no provincial tax)

References

• GST/HST rates by province

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