I'm pretty sure the bank does not have to notify the feds for check deposits.
It used to be only for cash greater than 10k.
Has that changed?
I think the ruling is for anything the bank finds 'suspicious' - which is activity not normally associated with the account holder. The Nest
has a nice write up on this. Also, I just read the IRS is using social media to help them identify assets taxpayers have that may trigger conditions for a successful audit