Customer has large check - deposits small amount into joint checking, cash out is over $10,000. Should Part I be on receiver of cash only or both account owners? Part III - Boxes 32, 34 and 35 all checked?

Treat the transaction as you would a cashed check over $10,000. You don't report the deposit at all.

IF THE CHECK IS PAYABLE TO BOTH ACCOUNT HOLDERS I WOULD ASSUME THAT THEY BOTH WILL BENEFIT FROM THE CASH- I WOULD COMPLETE 2 SECTION A's. IF CHECK IS ONLY PAYABLE TO THE INDIVIDUAL CASHING THE CHECK I WOULD COMPLETE 1 SECTION A.