There is no absolute legal maximum ceiling on the total amount of physical cash you are permitted to deposit into your bank account in a single transaction or visit. You can technically deposit thousands or even millions of dollars at once, provided you can satisfy the bank's compliance requirements. When depositing large sums of cash, banks will require you to complete detailed customer identification forms, provide your tax identification or social security number, and substantiate the legal origin of the funds to comply with anti-money laundering mandates. Depositing very large sums through an automated teller machine is often restricted by physical deposit slot capacities, requiring large transactions to be handled directly by branch tellers.