Depositing $1,000.00 cash is not suspicious but depositing $10,000.00 or more in cash is suspicious.
Depositing $10,000.00 or more is considered suspicious but is still okay to do but it can flag your account.
The amount of money that is suspicious to deposit is $10,000.00 in cash or more.
However there's nothing illegal about depositing $10,000.00 or more in cash at one time but if you do report $10,000.00 or more in cash at one time then the bank has to legally report that deposit to the IRS.
It does not mean you'll get investigated but if you continue to deposit $10,000.00 or more on a weekly basis then it can be looked at as suspicious.
Because lets face it unless you're a millionaire or are making legally a lot of money each week then you will not be depositing $10,000.00 or more in cash or checks into your bank account.
All money deposited into your checking account or savings account or money market account eventually gets reported to the IRS at the end of every year because the bank legally has to report all that money.
However you're free to legally deposit as much cash, checks etc as you want to into your bank account as long as the money was gotten or made legally.