We had an issue where the CJ Affiliate tag produces an incorrect result for CJ.

We are using the CJ Affiliate tag in a GTM server-side container, and have the GA4 client as trigger (according to the documentation). We are using a GA4 ecommerce (EEC) standard compliant datalayer on our website.

I was in contact with CJ's associate integration engineer because the calculated order total at CJ's end did not match the actual order value. He told us that the DCNTx parameter should be the item-level discount multiplied by the item-level quantity.
He showed us the full calculation that CJ uses to produce the total order amount:
(((AMT1 * QTY1) – DCNT1) + ((AMT2 * QTY2) – DCNT2) + … + ((AMTx * QTYx) – DCNTx) – DISCOUNT)
Here you can see that they multiply the item-level amount by quantity, but they do not do that for discount.

This produces an incorrect result in the following example - if you are using GA4 ecommerce standard:
Let's say you buy a product twice with a discount:

Product 1: AMT1 = 149, QTY1 = 2, DCNT1 = 22.35

(Order level discount does not apply).

The total order amount in this order would be 253.30

However, according to how CJ calculates the total order amount, they have a different result:
( (AMT1=149 * QTY1=2) – DCNT1=22.35 ) – DISCOUNT=0 )
which gives a total of 275,65.

As this is the way they calculate their order amount, he requested us the change the DCNTx parameter and multiply it by QTYx before sending to CJ.