The bank is required to file a currency transaction report for any amount over $10,000 or any amount just below this amount. They also have the discretion to file this for any amount.
What they do with this after the filing is beyond me, but I doubt it is very difficult for the guys in the black helicopters to compare:
1. Bob SS# 123-45-6789’s bank account with a couple of $120,000 checks from his brother and sister
2. Bob SS# 123-45-6789’s tax returns listing his job as Starbuck’s Barista and an income last year of $35,000
3. Bob SS# 123-45-6789 estimated tax payments for the year showing $0
