Lu, My area of expertise is in the Trust Compliance field. The questions that you might start with are these:
1) Does the trust department make disbursements in cash?
2) Does the trust department receive contribution of assets in cash?
3) When your trust officers are involved in leading or assisting in the cleaning-out of a client home (often because there is no family and the person has moved into a care-home or died) and they come across cash in the home, how do they handle that cash? What if the total cash in the home is more than $10,000?
I suspect that distributions and disbursements from your trust accounts are by check, wire, or ACH. Never have I encountered a situation where the trust department paid out cash. This make it much easier from a BSA perspective because you then wouldn't need to worry about the Currency and Foreign Reporting Requirements of 31 CFR 103.
In our case, staff receives refresher training that includes a reminder that as an internal policy, the bank does not accept cash deposits into a trust account. All cash transactions must be handled through the teller-line where the cash is used to purchase an official check which is then deposited into the trust. Because the teller-line is accustomed to reviewing bills for potential counterfeits and is more attuned to CTR reporting requirements, we feel good about the controls we have in place.
MountainHawk talked about reporting overdrafts of $10,000 or more. We don't report overdrafts to the BSA Officer, because as trustee or as agent it is the bank that controls the timing and dollar amount of asset movement. That said, overdrafts are monitored on a daily basis and the causes of the overdrafts are investigated. If there were anything that I would see on a daily basis on the overdraft report that caused particular discomfort, I would be the first to sound the alarm.
Hopefully this helps in getting you started. If you have any other particular questions, send me a PM and we can get in direct contact.