However, there is an overall maximum account balance limit of $ 500,000 which applies to all accounts opened for a beneficiary. (misaves.com)
There is also an aggregate account balance limit of $ 500,000. (savingforcollege.com)
Set Limits on Spending: Even if you make a larger deposit for the credit limit, some cards will also allow you to set a lower balance limit for that user. (thecollegeinvestor.com)