This is should be your primary card of use that is used for every day purchases (Credit or Debt Card). 

Guac will calculate your savings as you spend based on your spending from your Primary Card of Use. 

The Percentage you selected will be added to every transaction within the Spending Limit & Daily Spending Limit you set. 

* Remember this is just calculating your savings while your connected checking account remains your Funding Source. Please see Selecting your Funding Source for more information. 

* Similar to paying off your credit card payment each month, Guac is allowing you to fund your goals from your connected checking account BUT is calculating your savings from any Primary Card of Use.