The upsell is added to an order that is already paid. That has three practical consequences merchants ask us about regularly.
Discount logic is evaluated at checkout and is not re-evaluated when an upsell is added. A discount code your customer used in checkout does not reduce the upsell price, and the upsell amount does not change what the code already did.
Instead, you control the upsell price directly in the funnel: set a percentage or fixed discount on the offer itself. Show the saving prominently, it is your strongest conversion lever. See Offer discounts: percentage, fixed amount and quantity tiers.
Shipping costs are calculated at checkout and stay as they are. Two examples:
Tracking pixels (Meta, Google, TikTok and others) fire when the checkout completes, before the upsell decision. The upsell purchase happens after that, so pixels do not capture upsell revenue.
What this means in practice:
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