You know you’ve gotten them – those American Express or Chase gift cards that can be used just like a credit card, anywhere, to buy anything. Sounds great, except you can’t, really. Typically, these cards have pretty finite expirations, and after 12 months, a “service fee” starts being deducted from the card each month. Worse, you usually can’t use up the entire balance of the card, because you can’t overdraw them. Essentially, you have to keep track of the balance on your own, and hope that a merchant can split your purchase once you reach zero.

There’s a better way. Well, kind of. If you do a lot of online shopping from a single source, like Amazon or iTunes, you can easily apply the balance of your gift credit card to your account on one of theses services. This prevents the monthly charges, and allows you to use up the entire card on purchases.

The trick is to buy yourself a gift card. I’ll use Amazon as the example, but this should work for any other service that lets you maintain a gift balance in your account. From Amazon, simply click the “gift cards” like toward the top, and order a gift card (a digital one!) for the exact amount left on your gift credit card. Make sure you make your own email address the recipient.

When it comes time to check out, use your credit gift card number, its expiration, and whatever name the card company prefers you use. For some, like Chase, you’ll have to register the card on the bank’s website so it’s linked to your name. Others, like American Express, tell you to use a specific name, like “Gift Card Recipient,” and your own address. (Check the company’s website for how to use the cards online.)

Once you pay, you’ll get the gift code from Amazon in your email inbox. Simply copy-paste the code into the redemption center at Amazon, and this balance will hang around in your account until the next time you make a purchase. If you go over your balance, you can simply pay the difference with whatever real credit card you want, and actually use up the full amount of your gift!

Among the other benefits of this method is the fact that you can buy Kindle books this way. For some reason, Amazon only lets you purchase ebooks using 1-Click, which is linked to a specific credit card. However, if you have a gift balance, this is depleted first.

I should mention, too, that this is a great way of combining multiple credit gift cards. The amount in your Amazon account is one lump sum, so it doesn’t matter how many gift cards you send yourself – it all winds up in the same pot!