Fix the comparison
Use the same shopping country, exact item, unit count and intended quantity for every route. Note the displayed currency separately.
GUIDE 02 · CHECKOUT INPUTS
Compare the complete route, not one headline number.
A product-page price is one input to a purchase decision. Delivery, destination-specific charges, mandatory checkout fees and genuinely applicable discounts need their own evidence before they can be combined.
Read the offer
Record the item price, stock state and variant. Separate an unconditional price from a coupon, membership or basket condition.
Check the basket
Delivery can depend on destination, basket value, parcel weight and service level. Capture the option that is actually selectable.
Read checkout
Review the retailer-displayed checkout charges, discount conditions and payable currency before leaving the retailer to complete payment.
THE COST RECORD
Keep components separate until they are known.
A useful record has distinct fields for the product amount, delivery, retailer-displayed taxes or duties, mandatory retailer fees and valid discounts. Keeping them separate makes the evidence auditable and prevents one missing input from disappearing inside a total.
A zero should mean the source explicitly supports zero for that component in the stated context. If checkout has not revealed a component, label it unknown and avoid presenting the partial sum as a complete landed total.
Payment-provider or card conversion costs may sit outside the retailer's checkout and vary by customer. They should not be invented or represented as a universal retailer charge.
Is the discount usable?
Check expiry, minimum spend, eligible products, account status and whether the code can be combined with another promotion.
Is delivery comparable?
Compare selectable service levels on like-for-like terms rather than mixing the fastest route with the least expensive route.
Which currency is payable?
Preserve both the retailer's displayed currency and any clearly labelled converted view. Do not treat an estimate as the settlement amount.
What changed?
If checkout differs from the earlier observation, use checkout for the purchase decision and report the stale comparison for review.
FINAL CHECK
Use the comparison to investigate, not to skip checkout.
Reconfirm the exact variant, quantity, destination, delivery option, payable currency and checkout amount on the retailer's current checkout. The retailer controls the transaction, fulfilment and customer-service terms.
This checklist is an evidence-organising method. It does not predict an individual's tax treatment, card charges, delivery eligibility or final checkout outcome.