For cash deposits less than $10,000, a bank will usually just ask for a form of identification like a driver's license. Some banks also only allow deposits into your own account vs. someone else's account. If a small business uses an employee to make a cash deposit, that employee must have ID as well.
Ask for CTR
It is the bank's responsibility to file the CTR for your deposit of $10,000 or more. Most banks will ask for a driver's license or other form of identification, your Social Security number and your profession. They will then fill in the CTR report using information from your account. To protect yourself from an IRS audit, make sure the bank teller fills out the CTR on your behalf when you make the deposit. If you purposely deposit smaller amounts several times to try and avoid having to file a CTR, the federal government can charge you with "structuring." As of 2015, the penalty for structuring is up to five years in prison, a fine up to $250,000 or a combination of both jail time and fines. For structuring crimes that involve more than $100,000 in 12 months, the penalty is doubled.