You can deposit a million dollars in a bank since banks do not impose maximum deposit limits. However, consider several factors before you make your deposit. Such factors include deposit insurance limits and deposit hold times. The size of your deposit can also have a negative impact on your interest rate.
TL;DR (Too Long; Didn't Read)
Banks do not impose maximum deposit limits. There's no reason you can't put a million dollars in a bank, but the Federal Deposit Insurance Corporation won't cover the entire amount if placed in a single account. To protect your money, break the deposit into different accounts at different banks.
As of April 2018, the Federal Deposit Insurance Corporation insures deposited funds up to a maximum of $250,000 per account owner, per financial institution. If you have a joint account, you enjoy $500,000 of total coverage, and you can also extend your deposit insurance by another $250,000 for each pay-on-death beneficiary that you add to your account. If you have no co-owners or beneficiaries, you can split your money across several banks. Deposit insurance protects you from loss in the event that your bank goes bankrupt.
Federal law limits the amount of time that a bank can hold a check deposit. If you deposit a check for $1 million, your bank must make $100 available on the next business day and a further $4,900 available after two business days. The bank can holding the remaining funds for seven business days. If you open a new account with the money, then the bank can hold the whole check except for the first $100 for nine business days. Hold limits do not apply to savings accounts, so in theory your bank could hold a deposit into a savings account for any length of time.
Large Currency Transaction
If you deposit your $1 million as cash, your bank must complete a Large Currency Transaction Report for the Internal Revenue Service. This report contains your name, Social Security number, address, date of birth and your identification number and issue date. The IRS uses these reports to combat money laundering and terrorist activities. Large Currency Transaction Reports are only used for cash transactions, so if you deposit a check your bank does not have to complete this report. Banks must complete the reports on any cash transactions involving $10,000 or more.
Bank accounts do not have deposit maximums, but savings accounts and certificates of deposit do have tiered interest rates. Generally, you earn more interest for making larger deposits, but on most accounts, banks have a cutoff point after which interest rates drop. Some banks only pay high interest rates on deposits that do not exceed $250,000, while others pay the highest rate as long as your balance does not exceed $1 million. Therefore, you may earn more if you split your money among several accounts.