A Subaccount is an Account that you can establish under your American Express Serve® Account for another person age 13 or older. This Account is linked to, funded, and controlled by the Master American Express Serve Accountholder.
Subaccounts are a convenient and flexible way that you can give family and friends access to money, while seeing transaction activity and setting limits. You can create up to 4 subaccounts.
Go to serve.com and login to your Serve Account for additional information.