Write the conditions
Specify eligible products, dates, minimum spend and combinations. Important restrictions should be visible before ordering. Ask the responsible function to review applicable price-reduction obligations rather than treating a universal template as sufficient.
Show the calculation
Display price, discount, fees and total. If a code affects only part of the basket, explain which part. Do not imply that shipping fees are discounted when they remain unchanged. Users should be able to recalculate the result from the information shown.
Test edge cases
Try valid, expired, previously used and ineligible-basket codes. Explain rejection without exposing another customer’s information. Check keyboard and mobile use, and preserve the basket following an error instead of requiring people to restart.
Evaluate contribution
Separate orders, discounts granted and remaining margin. Heavy code use can shift purchases that would have occurred anyway. Reconcile returns and cancellations before concluding that the promotion was commercially beneficial.
- Define conditions
- Show total
- Test exceptions
- Evaluate
Worked example
Teaching example: item €100, discount €10, delivery €5; total €95. A product-only code does not make shipping free. Test the calculation on the page and in the order confirmation.
Check before moving on
These checkboxes are not saved.
Sources & method
Sources reviewed on 1 October 2026. Worked calculations use explicitly hypothetical inputs.
Topic provenance: Comment fonctionne les code promo pour les achats en ligne ? - search-engine-feng-shui.com (consulted capture: 2020-09-25). Search Engine Feng Shui. This record does not confirm an individual byline.
This guide is newly written in 2026. It does not reproduce the earlier text and is not attributed to its historical author.