You don't know. That's why there are rules about when to report large cash transactions. For example: https://www.irs.gov/newsroom/understand-how-to-report-

You don't know. That's why there are rules about when to report large cash transactions. For example: https://www.irs.gov/newsroom/understand-how-to-report-large-cash-transactions https://www.irs.gov/newsroom/understand-how-to-report-large-...