I have a friend who puts everything in the dishwasher. I mean everything. Cast iron pots, nylon baking sheets, and even crystal stemware that clearly screams “hand wash only” all go straight into the rack.
That’s how a lot of people use credit cards. They swipe blindly for everything, figuring the card can handle any transaction they throw at it.
Most of the time, it’s the right move. But some charges come out of the wash in worse shape than they went in. That stings more than ever now that cards carrying a balance charge an average of 22.36% interest, according to the Federal Reserve.
Here are four things I’d keep out of the dishwasher for good.
1. Taxes: The IRS fee eats your rewards first
Paying federal taxes with a credit card usually costs more than it earns you in rewards. The IRS’s approved payment processors charge a fee of about 1.75% to 1.85% on consumer credit cards.
On an $8,000 tax bill, that’s a $140 fee right off the top. A card earning 1.5% back would bring in just $120, so you’d lose money for the privilege of swiping.
I know the points crowd swears it pays off with the right card. And sure, a flat-rate 2% cash back card could squeak out a tiny profit on that $8,000 bill, about $20 after the fee. But carrying the balance for just one month at 22.36% APR costs you about $149 in interest, which wipes out that gain more than seven times over.
2. Medical bills: Your hospital would rather you not know this
Medical bills are almost always cheaper to pay directly than to put on a credit card. Many hospitals and doctor’s offices offer interest-free payment plans, and plenty of bills are negotiable if you simply ask.
Medical debt on a credit card will absolutely crush you with interest if you can’t pay the full balance. Call the billing office first, ask for an itemized bill, and get any payment plan in writing.
3. Cash advances: Banks charge you three times for cash
A cash advance is the most expensive way to use a credit card, period.
It stings you in three ways: First, the bank usually charges a fee of 3% to 5% upfront. Next, interest typically starts accruing that same day with no grace period. Lastly, cash advances usually have their own APR which is usually HIGHER than the already-ridiculous regular APR.
A quick $500 from the ATM can cost you $25 before you’ve even left the parking lot.
It’s not just ATM withdrawals, either. Casino chips, money orders, and some other cash-like purchases can get treated the same way. To top it off, these transactions usually don’t earn any rewards, so there’s no upside.
4. Anything you can’t pay off by the due date
Credit cards shouldn’t be used at all if you can’t afford the stuff you’re buying.
A big trip is a classic example. Putting it on a travel rewards card is smart, but only when you have the cash on hand to pay the bill in full that month.
Let’s say you charge a $4,000 family vacation and put $150 a month toward paying it off. At 22.36% APR, it’ll take 38 months to pay off, and you’ll hand the bank about $1,580 in interest.
Your tan fades in two weeks, but that balance sticks around for over three years!
Some things are better washed by hand
Credit card companies love customers who put every charge possible on credit. Every transaction processing fee, cash advance, and leftover balance is money that lands in their pocket instead of yours. They’d be thrilled if you never noticed.
So use your card for the everyday stuff you’d pay off anyway, and hand-wash the rest. If you want a workhorse that earns on every swipe, start with the best credit cards for 2026.
For everything else, pay with cash, debit, or a bank transfer.
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