Interest starts the day your purchase posts to your account — unless you have a grace period

Most credit cards give you a grace period, usually 21 to 25 days, between the date a purchase posts and the date interest begins. If you pay your full statement balance by the due date shown on your bill, you pay no interest on those purchases, even though the card issuer has already lent you the money.

If you don't pay the full balance, interest starts accruing on the unpaid portion immediately after the grace period ends. The exact number of days varies by card and issuer — check your cardholder agreement or call the number on the back of your card to confirm yours.

Cash advances and balance transfers work differently. Most cards charge interest on cash advances from the moment you withdraw the money, with no grace period at all. Balance transfers typically have no grace period either, though some cards offer a promotional period (often 0% for 6 to 21 months) before the regular APR kicks in.

Key Takeaways

  • A grace period means you have roughly three weeks after a purchase posts before interest starts, so paying in full by your due date avoids interest entirely.
  • Interest on unpaid balances begins the day after your grace period ends, calculated daily on the remaining amount owed.
  • Cash advances charge interest immediately with no grace period, and balance transfers usually have no grace period unless the card offers a promotional rate.
  • Your cardholder agreement lists your exact grace period length and which transactions (purchases, cash advances, balance transfers) are covered.
  • If you carry a balance from one month to the next, interest compounds daily, so the longer you wait to pay, the more you owe.

How the grace period actually works

The grace period clock starts when your purchase posts to your account, not when you swipe the card. A purchase might post the same day you make it, or it might take one to three business days depending on the merchant and your bank. Until it posts, the grace period hasn't begun.

The grace period ends on your statement due date. If your statement closes on the 15th and your due date is the 8th of the next month, you have until that 8th to pay without interest. Pay by then, and no interest charges appear on your next bill. Pay even one day late, and interest accrues on the unpaid balance retroactively — meaning you owe interest for every day from when the grace period ended until you paid.

The grace period applies only to purchases, not to other types of transactions. If your card offers a grace period at all, it must be at least 21 days — that's the federal minimum. Many cards offer 25 days. Some premium cards offer longer periods, though this is less common.

What happens when you carry a balance

Once the grace period ends and you have an unpaid balance, interest accrues every single day. Credit card companies use the daily periodic rate (your APR divided by 365) multiplied by your balance each day. This means the interest you owe compounds — you pay interest on interest.

If you owe $1,000 at 20% APR, you owe roughly $0.55 per day in interest (before compounding). By day 30, you owe about $16.44 in interest alone, plus the original $1,000. The longer you carry the balance, the faster the interest grows.

Minimum payments are designed to keep you in debt. A $1,000 balance at 20% APR with a 2% minimum payment means your first payment is $20, but $16.67 of that goes to interest and only $3.33 reduces the principal. You'll spend years paying off that $1,000.

Cash advances and balance transfers have different rules

A cash advance — withdrawing money from an ATM or getting cash at a bank using your credit card — starts accruing interest immediately. There is no grace period. Interest begins the day you withdraw the money, not the day it posts to your account. Most cards also charge a cash advance fee (usually 3% to 5% of the amount withdrawn) on top of the interest.

A balance transfer — moving debt from one card to another — typically has no grace period either. However, many cards offer a promotional 0% APR period on balance transfers, lasting anywhere from 6 to 21 months depending on the card. After the promotional period ends, the regular APR applies to any remaining balance. Read the offer carefully: some cards charge a balance transfer fee (usually 3% to 5%) even during the 0% period.

If you're considering a balance transfer to save on interest, calculate whether the promotional period is long enough to pay off the debt before the regular APR kicks in. A 12-month 0% offer on a $5,000 transfer means you need to pay roughly $417 per month to avoid interest entirely.

How to find your card's grace period and APR

Your cardholder agreement — the document you received when you opened the account — lists your grace period length and which transactions are covered. If you don't have it, log into your online account or call the number on the back of your card and ask for the agreement. You can also request it in writing; the issuer must provide it within 15 days.

Your Schumer Box (the standardized disclosure table on your card's website or in your welcome materials) shows your APR, grace period, and fees in one place. The APR listed is usually a range — your actual rate depends on your creditworthiness and the card's terms.

Different APRs apply to different transaction types. Your purchase APR might be 18%, while your cash advance APR is 24% and your balance transfer APR is 20%. Check which rate applies to the transaction you're making.

When interest doesn't start: promotional periods

Some cards offer a promotional 0% APR period on purchases, balance transfers, or both. During this period (typically 6 to 21 months), no interest accrues on may have access to transactions, even if you carry a balance. Once the promotional period ends, the regular APR applies to any remaining balance.

Read the terms carefully. A 0% offer on purchases might not cover balance transfers, or vice versa. Some cards charge a balance transfer fee even during the 0% period. Others require you to make at least one purchase per month to keep the promotional rate active.

If you're using a 0% offer strategically, calculate your payoff plan before you apply. If you have a $3,000 balance transfer on a 12-month 0% offer, you need to pay $250 per month to clear it before interest starts. If you only pay $200 per month, you'll owe interest on the remaining $1,000 at the regular APR when the promotion ends.

What to do if interest already started

If you've been charged interest and you believe it was a mistake, contact your card issuer immediately. If you missed your due date by a day or two and the grace period ended, the interest charge is correct — but you can still ask the issuer to waive it as a courtesy, especially if you have a good payment history.

If you're carrying a balance and want to stop the interest from growing, pay as much as you can toward the principal. Even an extra $50 per month reduces the balance faster and saves you money on interest. Some people use a balance transfer to a 0% card to buy time while they pay down the debt.

If you're struggling with high-interest debt, look at your options: a balance transfer card, a personal loan (which might have a lower rate), or a debt management plan through a nonprofit credit counselor. The longer you carry the balance, the more interest you'll pay.

Frequently Asked Questions

Does interest start if I pay part of my balance by the due date?

No — if you pay your full statement balance by the due date, no interest charges. If you pay part of it, interest accrues only on the unpaid portion, starting the day after the grace period ends. The part you paid is not charged interest.

Can I get a grace period if I already have a balance from last month?

No. The grace period applies only to new purchases made during the current billing cycle. If you carry a balance from the previous month, interest accrues on that balance immediately, and new purchases also accrue interest from the end of the grace period (or immediately, depending on the issuer's policy). Check your cardholder agreement for the exact rule.

What's the difference between APR and the interest I actually pay?

APR is the annual rate. The interest you actually pay depends on your balance and how long you carry it. If you owe $1,000 at 20% APR for one month, you pay roughly $16.67 in interest, not 20% of $1,000. The daily periodic rate (APR ÷ 365) is multiplied by your balance each day.

If I make a payment before my due date, does interest stop accruing?

Interest stops accruing only when your balance reaches zero. If you pay $500 on a $1,000 balance before your due date, interest continues to accrue on the remaining $500 until you pay it off completely or until your next grace period begins (if you're starting a new billing cycle with a zero balance).

Why does my interest charge seem higher than my APR?

Interest compounds daily, so the longer you carry a balance, the more you owe. Also, if you made multiple purchases on different dates, each one accrued interest for a different number of days. Your issuer calculates interest on the average daily balance, which accounts for all transactions and payments during the billing cycle.