How to agree bonuses with a client?

Question

contextual advertising

Given: a promoter and a potential client with whom cooperation is planned. There is a fairly old site with a noticeable number of branded returns and hits.
Task: Agree in cooperation: fixed block + motivational block (bonuses for attracting requests through the site).
Difficulties: The client is very skeptical about the bonus part. He says that there will be many calls on old, branded stories, which will not be the merit of a specialist. And it can be an endless argument with evidence: "whose merit is this?"
Question: Can anyone come across such layouts? How did you organize the collaboration? How did they differentiate between appeals (my and not my merit)? How was it measured correctly?

Answer 1

The client is absolutely right. Change by utm-tags, connect deeper analytics on referrers, returns to the site.