Three kinds of discount, two kinds of tax — get the order of operations right and your math is correct every time.
Line-item discount
Each line carries an optional discount (% or fixed amount). Applied before tax. Used for "this specific item is 10% off."
Subtotal discount
Applied after all line-item totals but before tax. Used for "10% off the whole quote" or volume tiers ("if subtotal > $10K, take 5%").
Promo codes
Tie a promo code to a campaign. When applied, it logs the source for attribution and applies either a percentage or fixed discount on the subtotal.
Tax per line
Each line item carries a default tax rate from the Catalog (e.g. 16% IVA for Mexico, 21% IVA for Spain, no tax for US-based clients in some states). The quote total respects each line's tax. Tax-exempt clients (validated tax ID) get 0%.
Subtotal-level tax
For simpler jurisdictions, apply a single tax rate to the post-discount subtotal. The template setting controls whether tax shows per-line or as a single bottom-line.
Tips
- For international quotes, list both pre-tax and gross-with-tax totals. Buyers in different countries optimize for different.
- Always show the discount amount, not just the discounted price. "$1,000 (10% off from $1,100)" reads more compelling than "$1,000".