What is one condition that affects billing clients for services in the NFL?

The correct choice highlights a critical aspect of the financial dynamics between agents and their clients in the NFL. Agents are generally prohibited from collecting their fees until their clients actually receive payment from their contracts or earned income. This policy protects players by ensuring they are not financially obligated to their agents without having first received funds from their professional engagements.

This condition aligns with the ethical standards set forth by the NFLPA, which emphasizes the importance of transparent and fair financial transactions between agents and players. Agents are expected to act in the best interests of their clients, and allowing them to collect fees only once the client has received payment ensures the client is not in a position of financial risk at the outset.

Other conditions, such as billing for practice squad positions or Pro Bowl appearances, may not apply universally or may have specific rules associated with them. Collecting funds directly from a team would also breach standard practices as agents typically do not receive payment directly from teams but rather through the players themselves upon completion of contract terms. Thus, the stipulation that payment to agents occurs post-client payment is a safeguard for both parties involved in their professional relationship.