Reconciliation
Treat discount fields as explanatory, not extra tax
Discount fields can explain why a stored tax amount is lower than a full-price expectation.
Inspect the source record
Inspect the source order's coupon or manual discount and the final stored tax lines after WooCommerce applied it.
Build a focused report
Use TaxPack's order/refund CSV discount_net_informational and discount_tax_informational fields to document context.
Read the result
The summary already uses stored tax lines. The informational fields are not a separate tax deduction to apply again.
A concrete example
An order with a CAD 10 coupon and CAD 4 recorded GST should contribute CAD 4 to the GST group.
Avoid this mistaken conclusion
Do not subtract an estimated coupon tax from that CAD 4; that would alter WooCommerce's recorded result.
Official references
These focused notes were drafted with AI assistance and checked against TaxPack behavior and the linked documentation.
These guides explain reporting workflows. TaxPack does not provide tax advice, calculate tax payable, or file returns.