Credit cards can be one of the most useful financial tools available to American consumers.

Used responsibly, they can help you build credit, earn cash back, collect travel rewards and get valuable purchase protections. But credit cards can also become extremely expensive when you carry a balance.

The biggest problem is that many people focus on the rewards and promotional offers while overlooking the details that determine how much their credit card actually costs.

Here are five things every credit card user should understand before swiping again.

1. The Minimum Payment Is Designed to Keep Your Account Current, Not Get You Out of Debt Quickly

Look at your credit card statement and you’ll usually see two important numbers:

Minimum payment due and statement balance.

The minimum payment is the smallest amount you generally need to pay by the due date to keep the account current. But paying only the minimum can leave you paying interest for years.

Credit card statements in the U.S. are required to provide information showing how long it could take to pay off your existing balance if you make only the minimum payment. They also show the payment amount that would pay off the current balance within 36 months, assuming no additional purchases.

That distinction is important.

Suppose you have a $6,000 balance and your minimum payment looks manageable. Paying the minimum may keep you from being considered late, but it doesn’t mean you’re making meaningful progress toward becoming debt free.

And because many credit cards calculate interest using a daily periodic rate or average daily balance, carrying the balance can become expensive.

What to do instead

If you can afford it, pay your statement balance in full every month.

If you cannot, pay substantially more than the minimum whenever possible and stop adding new purchases to a balance you are already struggling to repay.

2. A 0% APR Offer Does Not Always Mean “Free Money”

You’ve probably seen offers like:

“0% APR for 15 months.”

These offers can be extremely useful, but you need to understand exactly what type of promotion you’re receiving.

A typical 0% introductory APR offer means you don’t pay interest on qualifying balances during the promotional period, provided you follow the card’s terms.

But there is another type of promotion that deserves much more attention: deferred interest.

Deferred interest is commonly associated with certain store financing offers.

With a deferred-interest arrangement, you may be told that you won’t pay interest if the promotional balance is completely paid off within a specified period.

If you don’t pay the qualifying balance in full by the deadline, you could potentially be charged interest that had accumulated from the original purchase date. The CFPB specifically warns consumers about this structure.

That’s very different from a conventional 0% introductory APR offer.

Before accepting a promotional offer, ask:

Is this 0% APR or deferred interest?
When does the promotional period end?
What happens if I still have a balance?
Does the offer apply to purchases, balance transfers or both?
Is there a balance transfer fee?
What APR applies after the promotional period?

A 0% offer can be a powerful financial tool. Just make sure you understand what happens when the clock runs out.

3. Your Credit Limit Is Not a Spending Recommendation

If your bank gives you a $15,000 credit limit, it can feel like you’ve been given permission to spend $15,000.

You haven’t.

Your credit limit is simply the maximum amount of credit available under your account terms. Your personal spending limit should be determined by your income and budget, not by what your credit card issuer is willing to lend you.

There’s another reason this matters: credit utilization.

Credit utilization is essentially the amount of revolving credit you’re using compared with your available credit.

For example:

$3,000 balance ÷ $10,000 credit limit = 30% utilization

FICO considers revolving utilization as part of the “Amounts Owed” category, which accounts for roughly 30% of a typical FICO Score. Higher revolving utilization generally represents greater repayment risk in FICO’s analysis.

That doesn’t mean there is a universal magic number that guarantees a good credit score. Your credit profile contains many other factors.

It does mean that routinely maxing out your cards can be a problem even if you eventually make the payments.

A better approach

Think of your credit limit as an emergency ceiling, not a monthly spending budget.

If you have a $20,000 limit but only earn enough to comfortably support $3,000 of monthly spending, your sensible spending limit is closer to $3,000.

4. A Credit Card Cash Advance Is Not the Same as a Normal Purchase

Need cash?

You might think your credit card can function like an ATM card.

Technically, it can.

Financially, that’s often a very different story.

A cash advance can come with a separate fee and a higher APR than your regular purchase APR. More importantly, cash advances generally begin accruing interest immediately rather than receiving the normal purchase grace period.

For example, if you withdraw $500 from an ATM using your credit card, you could face:

A cash advance fee
A higher APR
Interest beginning immediately
An ATM fee
No normal purchase grace period

The exact costs depend on your card agreement.

There can also be other transactions that your issuer treats differently from ordinary purchases.

Before using your credit card for cash

Check the card’s:

Cash advance APR + cash advance fee + ATM fee + other applicable charges

If you need emergency cash, compare the total cost with other available options before using your credit card.

5. Paying Your Card in Full Can Give You an Interest-Free Period

Here’s one of the most useful things about credit cards that many people don’t fully understand.

You don’t necessarily have to pay interest every time you use a credit card.

Many credit cards offer a grace period on purchases. If your card has a grace period and you pay your balance in full by the due date, you can generally avoid interest on new purchases.

But there’s an important catch.

If you carry a balance, you can lose the grace period.

The CFPB explains that when you don’t pay your balance in full, interest can apply to new purchases depending on the card’s terms.

This is why someone who pays their credit card balance in full every month can have a completely different experience from someone who revolves a balance.

The simplest strategy

If your budget allows:

Use the card → earn the rewards → receive the statement → pay the statement balance in full by the due date.

That can allow you to take advantage of the card’s rewards while avoiding purchase interest.

Just remember that cash advances, balance transfers and other transaction types can have different rules.

Read next: How Credit Card Grace Periods Work

The Credit Card Strategy Most People Should Follow

You don’t need to avoid credit cards.

You need to understand what you’re actually buying when you use one.

A good credit card strategy is relatively simple:

1. Pay the statement balance in full

Don’t confuse the minimum payment with the amount you should ideally pay.

2. Treat your credit limit as a ceiling

Don’t increase your spending simply because your issuer increases your limit.

3. Understand your APR

Know the regular purchase APR, balance transfer APR and cash advance APR.

4. Read promotional terms

A 0% APR offer and a deferred-interest promotion aren’t necessarily the same thing.

5. Don’t chase rewards

A 5% reward isn’t valuable if you spend $100 you didn’t need to spend just to earn $5.

6. Watch your utilization

Your credit limit and reported balance can affect your credit profile.

7. Never ignore your statement

Your statement contains some of the most important information about your account, including your balance, minimum payment, due date, APR and fees.

Final Takeaway

Credit cards aren’t inherently good or bad.

The difference comes down to how you use them.

If you consistently pay your statement balance in full, understand promotional offers and avoid expensive transactions such as cash advances, a credit card can be a useful financial tool.

If you regularly carry balances and make only minimum payments, the same card can become one of the most expensive forms of consumer debt.

The smartest credit card users aren’t necessarily the people earning the most rewards.

They’re the people who understand exactly what their card costs them.

Frequently Asked Questions

Is it bad to pay only the minimum on a credit card?

Paying at least the minimum generally keeps the account current, assuming the payment is made on time. However, carrying the remaining balance can result in significant interest costs and a much longer repayment period.

Does paying a credit card in full improve your credit score?

Paying on time is important because payment history is a major component of FICO Scores. Payment history accounts for 35% of a typical FICO Score.

Is 0% APR really interest-free?

A genuine 0% introductory APR offer can allow qualifying purchases or balances to avoid interest during the promotional period, subject to the card’s terms. However, deferred-interest offers work differently and can result in previously deferred interest becoming payable if the promotional balance isn’t paid off as required.

Does using 100% of my credit limit hurt my credit?

High utilization can negatively affect your credit profile. FICO considers revolving utilization as part of the Amounts Owed category, which represents roughly 30% of a typical FICO Score.

Can I get cash from my credit card?

Yes, if your card allows cash advances. However, cash advances commonly involve fees and begin accruing interest immediately, often at a higher APR than regular purchases.

5 Things Your Credit Card Company Doesn’t Want You to Know