Originally Posted by PimpTheMonkey

Nope, any old charge will do. From the terms:

"You must have a payment due in each of the monthly cycles of the calendar quarter to be eligible for the Quarterly Cash Reward; a zero balance or a credit balance does not qualify."

and from the FAQ:

"What is a qualifying payment?
A monthly payment received on or before the due date, which is more than the monthly payment due is considered a qualifying payment.
A payment in full received on or before the due date is a qualifying payment."

I just have a small monthly bill go on this card. Just make sure that you change the bonus to direct deposit instead of a credit to the card. I didn't make that change at first, so when my first credit hit, I no longer had a balance on my account, so I lost out on one quarter's payment.