Related question- is it a withdrawal or Negotiable instrument?

If it's a check, select "negotiable instrument"

"Withdrawal" is used if the withdrawal is made with a non-negotiable withdrawal order such as a counter withdrawal.

This recently came up for me in my new job. While reviewing CTRs I noted that there was an on-us check cashed. It was written by Dad to Son. Son came in and cashed it. This is done several times per month. It was always my belief--and my previous banks never had an exam or audit issue around this-- that the account number would be recorded since it's an on-us check. Doesn't matter if Son is a customer or not. (If it's a transit check, no account number.) Lo and behold, it would appear my new bank has not been doing it that way. Since the only clear instructions I can find are an FIL from 1995, I contacted FinCEN to ask and haven't heard back. I'm not anticipating them telling me anything different from the FIL; however, one never knows, as they seem to tell one bank one thing and another bank something different (based on my interactions with them through three different banks).

Just refer them to the CTR electronic filing instructions.

22. Cash out amount for individual or entity listed in item 4
a. Acct. number(s) included in item 22

Item 22 Cash out amount: Enter the total cash out amount denominated in U.S. Dollars for the person recorded in Item 4. This amount cannot be greater than the amount in Item 27 “Total Cash Out" Record the account numbers of all accounts involved in the transaction(s). See General Instructions 12 and 13 for additional instructions on entering account numbers and amounts.