An AssociateTag is an alphanumeric token distributed by Amazon that uniquely identifies an Associate. It is the means by which Amazon credits an Associate for a sale. As we will see in a later section, the AssociateTag becomes part of the PurchaseURL, which is the URL used to purchase the items in a remote shopping cart. If you forget or choose not to include an AssociateTag in a CartCreate request and you want to add the AssociateTag later, you have to add it manually to the PurchaseURL.

The AssociateTag is optional in CartCreate requests. If an Associate does not include it in a request, however, he or she does not get credit for the sale and they do not receive Associate remuneration. If, however, a CartCreate request includes an AssociateTag, all future requests that modify the same cart must also contain the AssociateTag. If a request does not contain an AssociateTag, Product Advertising API returns an error.

Be careful when you specify an AssociateTag in the CartCreate request. Errors are not returned for inaccurate values.