← The Rules
Is it illegal to deposit $9,000 at a time to avoid the $10,000 report?
Short answer
Yes. Splitting cash into smaller deposits to avoid a bank report is called structuring, and it's a federal crime on its own, even if the money itself is legal.
The law targets the intent to dodge the report. A run of deposits just under $10,000 is exactly the pattern banks are trained to spot, and they can file a Suspicious Activity Report about it.
In Part 1 you tried $9,000 a day at a different bank each time. Four deposits in, someone was already looking at a screen with your name on it.
Sources: 31 U.S.C. § 5324 (Cornell LII)
US federal rules, explained for a story. Not legal advice.