Coupon REST API date_modified not updating when usage count changes

Hi @srdjan121,

I see why this feels confusing, you are correctly observing that the coupon resource is changing in practice when the usage count increments, and it makes sense to expect the modification timestamp to reflect that change. I am glad you raised it, and I am keen to help clarify how this works.

At the moment, this is the intended behaviour in WooCommerce. When a coupon is used, WooCommerce updates internal meta related to usage count, but it does not update the post modified or date_modified value for the coupon itself. From the REST API perspective, date_modified is only updated when the coupon post is explicitly edited, for example changing the amount, expiry date, restrictions, or other coupon settings in the admin.

Because of that distinction, usage count changes are treated as operational data rather than a content update, so they do not trigger a modification timestamp change in the REST API response.

If your integration relies on detecting coupon usage changes, the recommended approach is to monitor the usage_count field directly, or to hook into order related events instead of relying on date_modified for this specific case. You can also review the coupon data structure here to see which fields are expected to change via the API: https://woocommerce.github.io/woocommerce-rest-api-docs/#coupon-properties

If you would like this behaviour to change in the future, the best next step is to open a feature request so the product team can evaluate updating date_modified when usage data changes. That feedback is reviewed by the WooCommerce developers: https://woocommerce.com/feature-requests/woocommerce/.