One joint accountholder makes a deposit with cash back. The cash back requires a CTR be filed. (The deposited amount was small). I know to choose negotiable instrument cashed and I'm OK with listing the account number on the CTR but since it's a joint account do I list the other accountholder as a beneficiary (on behalf of)? I started to, and it's how the system kicked it out, but we don't really know that they benefited from the cash back portion. The check being deposited was payable to the person who was present.

If it was a withdrawal Question 23 would say that you would not be required to include the joint account holder. This isn't even a withdrawal; as you say, it's a check cashed transaction.

If you and I had a joint account and you split a $22,000 check into a $10,000 deposit and a $12,000 cash back, I'd be the first to tell you that I did not benefit from the $12,000!

Exactly. If the system hadn't have kicked it out the way it did I wouldn't have thought about putting them both on there for this situation (and I know the "system" isn't perfect and usually unreliable). Thanks.