This Card Pays up to 6% on Feeding Gremlins (aka My Children)

Between bottomless cereal bowls, gallon after gallon of milk, and the salmon my 6-year-old demands like he's prepping for a sushi exam, our monthly grocery bill is basically a second mortgage.

That's why I've come to love the Blue Cash Preferred® Card from American Express. It's one of the few 6% cash back grocery cards -- 6% cash back on U.S. supermarkets (on up to $6,000 per year in eligible purchases) and select U.S. streaming subscriptions -- making it a sneaky-powerful tool for parents, meal preppers, or anyone trying to offset the cost of feeding their tiny (or not-so-tiny) gremlins.

Here's how it works -- plus a little trick bigger households might be able to use to double the rewards.

Earn 6% cash back at U.S. supermarkets

The Blue Cash Preferred® Card from American Express is one of the most rewarding cash back cards for everyday life -- especially if your fridge is in a constant state of "we just went shopping" and "there's nothing to eat."

Here's the core rewards structure:

• 6% cash back on U.S. supermarkets (on up to $6,000 per year in eligible purchases) and select U.S. streaming subscriptions
• 3% cash back on U.S. gas stations and transit (including taxis/rideshare, parking, tolls, trains, buses and more)
• 1% cash back on other purchases
• Terms apply

That 6% grocery category is the main draw. If you're spending $500 a month at the grocery store, that's about $360 a year in cash back -- just for buying what you were going to buy anyway.

The card has a $0 intro annual fee for the first year, then $95. (See rates and fees.) Even after that applies in year two and beyond, the math beats almost all other grocery rewards cards.

Important note: Big box superstores and warehouse clubs like Walmart, Costco, and Target usually don't count as "U.S. supermarkets" for this card's 6% category. Same goes for most online grocery services and meal kits. To earn the full rewards, stick to traditional grocery stores like Kroger, Safeway, Trader Joe's, or ALDI.

The spending cap -- and a two-player workaround

There is one slightly annoying catch with this card: the 6% cash back only applies to the first $6,000 per year in U.S. supermarket purchases. After that, you drop to just 1% cash back.

In our house, we spend over $1,000 a month at the grocery store (including a bit of wine and craft beer). So we'd hit the $6,000 spending cap around July and miss out on a ton of extra rewards.

But here's a workaround if you have a partner or spouse with joint finances: each of you can apply for your own Amex Blue Cash Preferred, with separate account names.

That way, each card comes with its own $6,000 spending cap, effectively doubling your reward potential if you're high-volume shoppers.

Instead of earning $360 in yearly grocery rewards, you could earn up to $720 if you hit both caps.

Not everyone can realistically do this. But if your household regularly spends well over $500 per month on groceries and you manage money jointly, this strategy is worth considering.

If your spending is smaller or less consistent, you might be better off sticking with a flat-rate credit card. It's a simpler system, and you don't have to think about categories or spending caps -- just swipe and earn the same rate everywhere.

Don't miss the welcome offer (and intro APR)

Right now, new Amex Blue Cash Preferred cardholders can earn a $250 statement credit after spending $3,000 in the first 6 months. Terms apply.

That's a great upfront win, especially with the $0 intro annual fee for the first year, then $95.

Between that welcome offer and the elevated grocery rewards, your year-one payback can be really big -- even before you count streaming, gas, or other spending rewards.

There's also a 0% intro APR on purchases and balance transfers for 12 months. After that, a 19.74%-28.74% Variable APR applies.

The bottom line

Feeding kids isn't cheap. But when you've got a credit card that gives you cash back on the chaos, at least you're getting a decent discount.

And if your grocery bill keeps climbing year after year like mine, you might as well earn the absolute most for every dollar you spend.

Compare all the best cards for groceries and gas here -- and find the right fit for your family.