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If you're looking to buy in bulk, order groceries or purchase household items, there's a good chance you shop at Costco or Amazon.
Both retailers have a great selection of items and offer discounts on a variety of essentials from toilet paper and water to outdoor furniture and electronics.
While you may already receive special promotions for being a Costco or Amazon Prime member, you can increase savings by using one of the store's co-branded credit cards.
Costco offers the Costco Anywhere Visa® Card by Citi, whereas Amazon offers four cards: Amazon Prime Rewards Visa Signature Card, Amazon Rewards Visa Signature Card, Amazon Prime Store Card and Amazon Store Card.
All of these cards have no annual fee, though membership to Costco or Prime may be required depending on the card you open. To maximize savings at Costco or Amazon, you should consider if a card from one retailer or both may deserve a spot in your wallet.
Below, CNBC Select breaks down the basics of each card from rewards and added perks to membership requirements and fees. For our comparison, we'll focus on the consumer cards mentioned above, though there are business versions available.
In order to qualify for the Costco Anywhere card, you'll need to be a Costco member. The cost for membership starts at $60 for Gold Star and doubles to $120 for Gold Star Executive. The level of membership you have doesn't matter and you can sometimes score a deal on joining through offers provided on Groupon.
Note: Like its name suggests, you can use this card anywhere, but it's only available if you have a current Costco membership in your name. So if you cancel your Costco membership after opening the card, your card will also be canceled.
Two of the four Amazon cards require Prime membership — the Amazon Prime Rewards Visa Signature Card and the Amazon Prime Store Card. Prime costs $119 for an annual membership or $12.99 per month (which is $36.88 more than an annual plan).
However, there's a chance you can piggyback off someone else's Prime membership through an Amazon Household. If you join a Household that has a Prime membership, you can qualify for one of the Amazon Prime Rewards cards.
In order to keep the Prime version of the cards, you'll need an active Prime membership. If at any time you cancel your Prime membership or are removed from an eligible Household, your card will be downgraded. Amazon Prime Rewards Visa Signature Cards will switch to the Amazon Rewards Visa Signature Card and Amazon Prime Store Cards will transition to the Amazon Store Card.
Note: You can only use the Amazon store cards on Amazon.com, Audible.com and select Pay with Amazon merchants. There are some exclusions, including purchases at the Amazon-owned Whole Foods Market and other transactions, such as video rentals and digital add-on subscriptions, like Hulu. (Check out the best store cards.)
The Costco card and Amazon cards offer competitive rewards programs that benefit different types of consumers. Here's the breakdown:
The Costco credit card is geared toward travelers and foodies with the highest cash-back rates on those purchases — even higher than on Coscto purchases. However, 2% cash back on Costco purchases is still a good offer considering many of the best cards to use at Costco offer 1% to 1.5%.
Meanwhile, if you prefer to buy groceries at Whole Foods Market or shop on Amazon, you'll likely want to stick with the Amazon cards.
When it comes time to redeem rewards, the Costco card has a pretty big setback: You only receive cash back once a year via an annual reward certificate after your February billing statement closes. This can make it hard if you don't live near a Costco warehouse. (Learn more about redeeming Costco credit card rewards.)
In comparison, Amazon cardholders can redeem rewards at any time. Redemption options include statement credits, gift cards and the ability to apply points at Amazon checkout.
Winner: If you want a welcome bonus and the most flexible reward redemptions, the Amazon cards are the clear winner. But if waiting until every February to receive Costco rewards doesn't bother you and you don't mind forgoing a bonus, consider the type of categories you spend the most in.
If you want to earn travel, gas and dining rewards, the Costco card provides the highest cash-back rates. Plus you'll earn more on Costco purchases compared to the Amazon card. But if you rather maximize rewards at Amazon, Whole Foods Market and drugstores, the Amazon cards are the better choice.
All cards have no annual fees, though membership may be required.
Special financing and APR
The Costco card doesn't offer an intro 0% APR period, and all purchases and balance transfers will incur a standard 15.24% variable APR.
The Amazon store cards are the only ones that currently offer special financing with no interest on Amazon purchases of $150 or more if the entire purchase amount is paid in full within six, 12 or 24 months. Here's a breakdown of the offers:
After the special financing offers end, there's a 25.99% variable APR. Keep in mind you should aim to pay off your balance before the no interest period ends to avoid retroactive interest charges. Also known as deferred interest, this is when you incur a charge for all the interest you accrued since you made the purchase.
It's also important to note that if you have the Amazon Prime Store Card, special financing offers can't be used with 5% back rewards. You'll have to choose whether you want to earn rewards on a purchase or use a special financing offer.
The Amazon Visa cards both have a 14.24% to 22.24% variable and no 0% APR periods.
Foreign transaction fee
The Costco card and Amazon Visa cards have no foreign transaction fee, so you can use them outside the U.S. without incurring the 3% fee other cards may charge. If you have one of the Amazon store cards, you won't be able to use the cards abroad.
Winner: All the cards break even on the annual fee, and the Costco card and Amazon Visa cards are both good for foreign travel. However, if you're in the market for special financing offers, the Amazon store cards are the best option since they're currently the only cards providing introductory interest-free periods.
The Costco Anywhere Visa Card offers:
Amazon store cardholders don't receive any of these perks.
Winner: Amazon Visa cardholders receive many of the same perks as the Costco card, plus more.
At the end of the day, the best credit card for you depends on where you prefer to shop. If you primarily shop at Costco, then the Costco Anywhere Visa Card is the better choice. But if you favor Amazon, consider one of the Amazon cards.
If you shop at both retailers and are torn between which card to open, here's a quick breakdown to help you assess the best one for your needs:
While the Costco card and Amazon cards can provide loyal customers a wide range of perks and rewards, you may feel held back by the potential membership requirements and limited grocery rewards.
If you want to earn up to 6% cash back at mainstream supermarkets outside of Costco and Whole Foods Market, look to alternative grocery rewards cards. You can also consider no annual fee cards that don't require membership.
Information about the Amazon Prime Rewards Visa Signature Card, Amazon Rewards Visa Signature Card, Amazon Prime Store Card and Amazon Store Card has been collected independently by CNBC and has not been reviewed or provided by the issuer of the cards prior to publication.