Scenario:

Customer deposits two checks into a new account. The total deposit exceeds $5,000 but both checks are returned; returned reasons are "Refer to Maker" and "NSF". Then, five days after opening, account begins to receive ACH debits totaling $49,000 from another financial institution.

For purposes of a SAR, would the above scenario be considered "Check Fraud" and "Other - ACH Fraud"?

Have you been in contact with your "new customer"? Any explanation? I don't think you want them as a customer, as you are off to a rocky start. I think your purposes for an SAR are fine.

I have always considered ACH to be similar to checks and have marked the box for Check Fraud on the SAR. The customer might be involved in a credit card bust-out scheme and you might want to contact local law enforcement since time is very important in these cases. Then as Okie suggested, get rid of the account ASAP.

It sounds as if both checks and ACH are involved--since you're not entirely sure what the situation is, I would mark both ACH and check fraud on the SAR.