Look, I’m not afraid to admit it: I’m a cash back rewards fanatic. I have hand-selected the credit cards in my wallet based on my typical spending patterns, and I optimize their usage accordingly. This year, it really worked out well, too: I managed to get over $550 back on grocery purchases alone!

I didn’t spend some obscene amount of money on food each month (though honestly, it can feel that way sometimes). I also didn’t manufacture any spending in order to earn these rewards. So, how on earth did I manage to get more than $550 in statement credits over the last 12 months, just for feeding my family as I usually do?

Honestly, it was as easy as swiping my credit cards.

Why I Focused on Groceries

I have two young boys who could rival grown men in an eating contest. Suffice it to say, we spend a fair amount on groceries each year.

My average spending over the last 12 months, for example, was $795 a month, for a total of $9,544 on groceries. This doesn’t count the occasional dinner out or Pizza Fridays in the school cafeteria… only grocery store purchases.

Optimizing My Spending

I already know that a large portion of my budget goes toward food each month, so I wanted to make sure that I picked credit cards optimized for that kind of buying. The Blue Cash Preferred from American Express was, of course, my first choice.

This card offers members a whopping 6% cash back on grocery store purchases all year long, for up to $6,000 in purchases each calendar year. This means that when I spend up to $6,000 on food in a given 12-month period, I walk away with $360 in statement credits. So, that’s where they majority of my grocery cash back came from over the past year.

By the way, any grocery store purchases beyond that $6,000 maximum are at a cash back rate of 1%. I did go over on this card’s grocery spending by $17, netting me an extra $0.17 in cash back. This brought my to a total of $360.17 from American Express.

Having a Back-Up Plan

I knew full well that I would go over American Express’s allotted $6,000 limit with the Blue Cash Preferred, as I do each year. So last summer, I set out to find a backup card that could earn me more than 1% on my grocery purchases, without also adding to my annual fees each year.

Enter the Discover it Card.

This card is underrated, in my opinion. It has rotating categories, meaning that each quarter, you’ll have the opportunity to earn 5% back on specific spending categories. You’ll need to remember to opt in, and after the quarter ends, your spending categories will change.

Well each year (since I started paying attention, at least), Discover includes “grocery stores” as one of its quarterly categories. During this time, I earn 5% back on up to $1,500 in grocery spending. This means that I could give my Amex a three-month break, jumping my high-rewards threshold from $6,000 to a total of $7,500 between the two cards.

It gets better, though. During the first year of card ownership, Discover will double your rewards earnings with its Cashback Match. So, the 5% I earned on groceries by shopping during the designated quarter would actually turn into 10% at the end of the year.

That brings my Discover rewards bonus earnings to $150, thanks to Cashback Match. Added to my American Express rewards, I earned $510 back using these two cards and their high-rewards promotions.

Making the Best of the Rest

Of course, I wound up spending more on groceries in the last year than the combined $7,500 of those two cards’ highest rewards tiers. This means that I needed to use the best-worst card choice for my remaining grocery spending, in order to squeeze out every last penny of rewards.

Since I am still in my first year with the Discover it Card, this was the obvious choice. All everyday spending is essentially doubled from 1% to 2% at the end of the year, thanks to Cashback Match. This is double the cash back that my American Express would have offered on the excess spending.

I spent a total of $2,044 additional on groceries this year, after maxing out the other two cards’ benefits. This means that I earned another $41 from Discover, bringing my total grocery-related cash back earnings to $551 for the last 12 months.

Your monthly grocery bill may be less (or more) than mine. No matter what, though, it’s important to use a cash back card that optimizes your spending habits. This may also mean using more than one card throughout the year to squeeze as much cash back out of your spending as you can.

This year’s earnings just further confirmed what I already knew: cash back cards can be incredibly lucrative… and you don’t even change the way you spend!