Iffor some reason, the Promotion Code field in the Web Store Shopping Cart andcheckout is not appearing even if allpossible setting have been checked, see if all Promotion Codes created are still Active and not expired.
There should be at least one Promotion Code that is activeand not expired for the Promotion Code field to appear in the Web Store.
User can review the Promotion Codes with the steps below:
1. Navigate to Lists > Marketing > Promotions.
2. Check Show Inactives checkbox to display additional column.
3. User can see Start Date and End Date columns.
Note: If user is not able to see Start Date and End Date columns click Customize View > Add both columns > Click Save.
Other option is to View each promotion.