Sending cash to friends and family? Before you reach for that credit card, grab a calculator. It’s time to do a little math.

With most everything you purchase online or through apps, credit cards have the edge. With plastic, you have chargeback rights. If you’re overcharged or receive the wrong item, broken merchandise or nothing at all, your card issuer will make it right. And if you use a rewards card, you collect points or miles, too. Win-win.

But it’s different story when you’re sending money through peer-to-peer platforms. Many of them (like Google Pay, Popmoney and Zelle), don’t allow consumers to use a credit card to send cash.

Others (like Cash App, PayPal and Venmo), allow credit cards but also charge a fee for the privilege – often about 3%.

See related: How to choose a P2P payment service

The hidden costs of using credit cards to send money

Choose a credit card to send money and you might also end up paying additional fees to your card issuer. That’s because the combination of some peer-to-peer apps with certain cards are coded as cash advances, rather than purchases.

For many cards, that cash advance code triggers a higher interest rate that kicks in the moment you make the transaction, as well as a separate cash advance fee that’s often $10 or 5% of the transaction – whichever is higher. (Currently, the average interest rate for cash advances is 24.8%, while the average APR for purchases is 16.05%.)

So the combination of peer-to-peer service fees, credit card cash advance fees and that higher interest rate (with no grace period) could make sending a few hundred dollars a bit more costly than you’d planned.

No chargeback rights with credit cards

The real kicker: Unlike other venues, you don’t have chargeback rights when you use credit cards to make peer-to-peer money transfers.

When you present your credit card in an online or brick-and-mortar store, there’s a merchant involved – and the law provides chargeback rights for your protection in case you don’t get what you were promised in the deal. But in a peer-to-peer money transfer, there’s no merchant, so currently the laws don’t give consumers any chargeback rights, says Christina Tetreault, manager of financial policy for Consumer Reports.

“The chargeback right requires a merchant,” says Tetreault. “One of the hoops a consumer has to jump through is to try and work it out with the merchant.”

If you use a peer-to-peer service and send the wrong amount or send the money to the wrong person, most platforms advise that the only way to get it back is to contact the recipient and ask them to return it. And that’s often the same whether you use a credit card, debit card, bank account or funded account on the platform.

“Be doubly sure when you’re sending the money that you’re putting in the correct information,” says John Breyault, vice president of public policy, telecommunications and fraud for the National Consumers League. “It’s still a buyer beware world when it comes to peer-to-peer.”

The solution

If you’re sending money and want to use a credit card, it pays to do a little sleuthing first. Check out the peer-to-peer site. Does it allow users to send money with a credit card? If so what, if any, fees does it charge?

On some platforms (PayPal is one), you could see similar fees for using a debit card – while sending from a bank account or funded account on the platform is free.

The good news is that many peer-to-peer platforms clearly disclose it when there’s an extra charge to use a credit card, says Tetreault. With Venmo, for example, you’ll get a pop-up message.

Harder to decipher: Will credit card transactions on the platform be treated as a cash advance? If your preferred platform doesn’t post this information, you might need to contact customer service. (And how quickly and easily you get an answer can tell you a lot, too.)

Ask your card issuer the same question: Are peer-to-peer money transfers on the platform you’ve chosen treated as a cash advance? If they are, what’s the interest rate, and what’s the cash advance fee?

“What I would suggest is to ask that question, via email, of your financial institution,” says Tetreault. “It may be in their FAQs. And you want to save that email. If you have it in writing, if there’s an issue later, you’re better positioned to contest that fee.”

But “the hard truth is you may not be able to find out ahead of time,” she says.

Another solution: Opt to use a credit card issued by a credit union.

“With credit unions, the APR is usually the same” for purchases and cash advances, says John Bratsakis, president and CEO of the Maryland and District of Columbia Credit Union Association.

Likewise, with American Express cards you pay your regular interest rate and no cash advance fees on peer-to-peer transfers, says Elizabeth Crosta, vice president of public affairs for American Express.

And credit cards from U.S. Bank register peer-to-peer money transfers as regular purchases – with no cash advance fees or cash advance APRs, says Rick Rothacker, spokesperson for the bank.

See related: How do credit card APRs work?

What’s your reason for using a credit card?

Take a good look at the reason you’re using a credit card, too. If you want chargeback rights, that’s not an option. If you’re doing it for the rewards, will the value of those points or miles be eaten up by extra fees or a higher interest rate you have to pay to use the card?

And if you’re using a card because you don’t have the cash, that might be a good reason to rethink the idea of sending money in the first place.

That’s a huge red flag, says Bruce McClary, vice president of public relations at the National Foundation for Credit Counseling.

“The need to convert credit into cash is what really gets my attention – because that hints at a lack of savings,” he said. “It’s a reality a lot of people are facing, especially now.”

Cash advances aren’t as expensive or risky as payday loans and car title loans, but they should be among your last resorts. If you’re looking for short-term relief, you could ask your credit card issuer for help, or find out if you qualify for a personal loan. You could also borrow from a family member or trusted friend, but be wary of the potential relationship toll if you can’t pay them back.