For the Round Up feature, another account will need to linked from which you want Compound Banc to monitor to track the spare change from your everyday purchases. This monitoring account can be a checking account or credit card.
Once your spare change round-ups total the $10 bond purchase threshold, the actual bond purchases will be debited from whatever funding source you linked to buy bonds at the time of signup, regardless of your monitoring source.
Some customers use their checking account as both their funding and monitoring source as their debit cards tend to be most actively used for their everyday purchases.