More and more people switch to the new Google Analytics Universal tracking code. But by doing that they create a new 'problem'. The Google Analytics Universal scripts handles visits from new sources during an existing visit as a new visits while the old analytics code didn't do that.
Let's visualize that:
The second line shows what happens in the new situation. The payment providers get all the revenue attributed to them. This occurs when visitors have to click on a link to return to your thankyou page. Google Analytics will see a new referrer and start a new session with the payment provider as the source.
The most simple solution is to add the domains of the payment providers to the "Referral Exclusion List" in the property settings like this:
But this only works if you have a few domains as payment provider. If you have an international site with payments from hundreds of banks you need this solution:
This parameter must be added to the "return URL" you configured, often your thankyou page. So for example, your thankyou page URL could look like this:
Google Analytics will see this nooverride parameter and will ignore the new source. This leads to the first situation showed in the first image, the revenue will be attributed to the right source. And that's what we all want.