What is a 0% intro APR on a credit card?

A 0% intro APR offer lets you carry a credit card balance — or complete a balance transfer — without paying interest for a defined promotional period, typically 12–21 months. After the period ends, the standard APR applies to any remaining balance.

A 0% introductory APR is a temporary promotion in which a credit card issuer waives interest on purchases, balance transfers, or both for a defined period after account opening. The CFPB's guide to credit card APRs notes that promotional rate terms must be clearly disclosed in the card agreement, including the exact end date and what rate will apply afterward.

How the promotional window works

During the promo period, purchases you charge (or balances you transfer in) accumulate on your account but accrue no interest. You are still required to make at least a minimum payment each billing cycle. If you miss a payment, most issuers can terminate the promotional rate under a 'penalty APR' clause. The FTC's credit card explainer advises reading the penalty-APR trigger conditions in the card's terms.

The promo period typically begins at account opening — not at first use.
Missing a minimum payment can cancel the 0% rate early and trigger a penalty APR.
Balance transfers under a 0% offer usually carry a one-time transfer fee (often 3%–5%) even though no interest accrues.
After the promo ends, the remaining balance is subject to the card's standard APR, often 20%+.
Some retail financing uses 'deferred interest' instead of true 0% APR — a critical difference (see below).

0% APR vs. deferred interest: a critical distinction

Bank-issued credit cards typically offer true 0% APR — no interest accrues during the promo period, and any remaining balance at the end simply starts accruing at the standard rate going forward. Deferred interest, more common in retail store financing, works differently: interest accrues behind the scenes the entire time, and if you have any balance left at the promo end date, all of that deferred interest is charged at once. The CFPB has published consumer warnings specifically about deferred-interest programs.

What happens when the promo period ends

Any balance remaining at the end of the promotional period begins accruing interest at the card's standard purchase APR. The Federal Reserve G.19 release shows average assessed credit card rates above 20% in recent periods. If your plan was to pay off a large purchase over 18 months at 0%, make sure your payment schedule actually gets you to zero before month 18 — not month 20.

What regulators say

Credit card issuers must clearly disclose the promotional APR, the duration of the promotional period, and the rate that will apply after the promotion ends. — CFPB
The CFPB warns consumers about deferred-interest offers, where all accrued back-interest can be charged in a lump sum if any balance remains at the promotional period's end. — CFPB
Federal Reserve G.19 data shows assessed credit card interest rates have averaged above 20% APR — the rate that applies once a 0% promo expires. — Federal Reserve G.19

Key takeaways

A 0% intro APR suspends interest for a defined period — not forever. Know the exact end date.
Missing even one minimum payment can trigger a penalty APR that ends the promo early.
Balance transfers at 0% still usually carry a 3%–5% one-time transfer fee.
Deferred interest is not the same as 0% APR — all back-interest hits at once if any balance remains.
Plan your payoff schedule to reach zero before the promo window closes.