https://www.amazon.com/gp/help/customer/display.html?nodeId=15399401

Assign a Checking Account as a Payment Option

If you don't have a credit card, don't worry, Amazon.com lets customers pay for products on Amazon.com with an ACH-enabled U.S. checking account.


To use your checking account as a payment option, do the following: 1. Click Add a checking account at the Shipping & Payment stage of the checkout process.   
2. Enter the bank routing number (also known as the ABA code).   
3. Enter the Account number (the account must be an ACH-enabled checking account at a bank branch located in the U.S. If you're unsure whether your account is ACH-enabled, please contact your bank).   
4. Enter the name and the address of the principal account holder.   
5. Enter the principal account holder's valid U.S. driver's license number (or state-issued ID number) and the issuing state.   


Note:
• You can use any checking account provided your account is a personal account located at a branch in the U.S. We don't accept savings, corporate, or business bank accounts.
• Routing numbers are always 9 digits long. Account numbers may be up to 17 digits long. Some banks list the routing number first on the check, while other banks list the account number first.