Read the retailer terms
Determine whether the retailer states that taxes or duties are included, collected at checkout or excluded.

DEEP DIVE · DESTINATION CHARGES
Cross-border charges can depend on destination rules, order value, product category, shipping terms and the party collecting them. A comparison should report what the retailer checkout shows without predicting a shopper's legal liability.
Determine whether the retailer states that taxes or duties are included, collected at checkout or excluded.
Record separately labelled tax, duty, handling and mandatory service charges for the fixed destination and basket.
Distinguish retailer-collected amounts from charges that a carrier or authority may request later.
Describe only what the retailer source supports and direct shoppers to the relevant authority for current rules.
EVIDENCE BOUNDARY
A retailer may say duties are included, prepaid, collected at checkout or payable later. Use the retailer's current wording and do not invent a missing charge treatment.
Thresholds and exemptions can change and can depend on facts that a public site does not know. The absence of a charge at one checkout moment does not prove that no later charge can apply.
For privacy and accuracy, a comparison should not collect unnecessary identity or customs information. Use only what the retailer page, retailer-provided data or destination checkout actually supports.
Use only when the retailer expressly says the displayed amount includes the charge.
Record a separately itemized charge visible for the fixed basket and destination.
Do not add an invented estimate; explain that the known subtotal is incomplete.
Keep the comparison from claiming a final landed total.
SAFE SUMMARY
Facts come from the retailer page, retailer-provided data, terms or destination checkout. Possible later charges should be clearly qualified. Personalized tax or customs advice is outside the comparison.
If a material mandatory charge cannot be verified, the route can still show the known item and delivery components but should not be labelled a complete landed total.