What is the minimum amount of deposit in check form that a bank is required to report to the IRS?

Answer 1

Any banking transaction of $10,000 or above is automatically reported to the Treasury deparment. It can be a deposit, withdrawal or a transfer of funds between accounts.

This isn't limited to banking transactions, by the way; any commercial transaction involving a single cash payment of $10,000 or more is reportable. If you buy a car and pay in cash, check or credit card a single payment of $10,000 or more that is a reportable transaction. If you finance the vehicle, only a down payment of $10,000 or more or a single loan payment of $10,000 or more is reportable.

Banks are also now required to report aggregate transactions of a similar nature or between the same parties that exceed $10,000 over a short period of time.

This is not reported to the IRS but is reported to the Treasury department through the Controller of the Currency.

The primary reason for this is to track transactions that may involve illegal activity such as money laundering, drug transactions, etc.