If you follow my gold credit card portfolio to get your share of $1,000 cashback rewards every year, you might notice the biggest bottleneck to squeeze even more cashback dollars is the caps put in the top two cards. Specifically, Citi® Dividend Platinum Select® Card has an annual cashback cap of $300, effectively limiting the 5% cashback priviledge to the first $6,000 grocery and gas station spend every year, and MBNA Cashback Card has a monthly cap of $25 for 10% cashback opportunities for grocery and dining charges.

How to break such barriers? If you have a family, you might want to get a second card of each type by applying in your spouse's name. That's what I did last month -- now I have two Citi Dividend cards and two MBNA Cashback cards.

The next challenge is how to allocate the charges. Based on my recent spending patterns, my family charge around $750 in groceries, $300 in dining out and $130 in gas refilling. (Around $250 monthly spend on groceries is on Walmart or Target, which does not fall into the eligible 5% or 10% cashback category.) Besides, we also have around $500 credit card charges in other categories.

If you run some calculation based on these numbers, you may realize I have no way to max out the reward caps from the four cards. The best choice I have, is to max out the $25/card monthly cap on two MBNA Cashback card by charging $300 dining out and $200 groceries, and leave another $300 groceries and $130 gas filling to Citi Dividend. Assuming any other credit card charges give me 1% cash back, I should be able to earn $500 * 10% + ($300 + $130) * 5% + ($250 + $500) * 1% = $79/month.

I must recognize that the incremental benefit from such cashback arbitrage is diminishing, and it isn't worth more time to squeeze the last reward dollar, but if you have a larger family to support, or have a larger spending base than mine, a second card should help your bottom line much more. Good luck!