What “variable APR” actually means
A variable APR is calculated as an index rate plus an issuer margin. On US consumer credit cards, the index is almost always the prime rate as published in the Wall Street Journal. The margin is set by the issuer at account opening and stays constant for the life of the account; what moves is the index.
A typical low APR card disclosure might read “13.49% to 23.49%, depending on your creditworthiness, based on the prime rate.” That means the issuer is offering margins from roughly 5.00% to 15.00% over prime, with your specific margin set when you are approved. As the prime rate moves, every cardholder’s APR moves by exactly the same amount, just from different starting points.
The prime rate itself is set by major commercial banks but tracks the federal funds target rate closely (typically prime equals fed funds plus 3 percentage points). It is published in the Federal Reserve H.15 release. When the Federal Open Market Committee changes the federal funds target, the prime rate follows within days, and credit card APRs follow within one to two billing cycles.
What “fixed APR” meant historically
A fixed APR is a rate that does not change with an index. Through the 1990s and early 2000s, a substantial portion of US credit cards carried fixed APRs. The marketing pitch was straightforward: the rate at account opening would stay the rate for the life of the account, predictable and unchanging.
The catch in fixed APR cards was that “fixed” did not mean permanent. Issuers could change the rate at any time with 15 days’ notice for any reason, and they did. The practical experience was that fixed APRs were quasi-fixed for low-risk accounts and adjusted upward for higher risk accounts whenever the issuer wanted to reprice.
The CFPB and various consumer protection bodies documented widespread cardholder confusion about what “fixed APR” meant in practice. The Federal Reserve’s public correspondence on the 2008 to 2009 financial crisis includes discussion of issuer practices around fixed APR repricing as one of the catalysts for the legislative response that became the CARD Act.
What the CARD Act of 2009 did
The Credit Card Accountability Responsibility and Disclosure Act of 2009, implemented via amendments to Regulation Z (12 CFR 1026), made it substantially harder for issuers to raise the APR on existing balances. Among other provisions, the Act:
- Prohibited rate increases on existing balances except in narrow circumstances (a fixed-rate intro period ending, a penalty APR triggered by 60+ days late payment, or the account being a variable APR that moves with an index).
- Required 45 days’ advance notice of any significant change in terms, up from 15 days previously.
- Required that any rate increase on existing balances apply only to balances acquired after the increase took effect, not retroactively.
- Mandated that the issuer review accounts that had been subjected to a penalty APR every six months and restore the standard APR if the cardholder had made on-time payments during that period.
The exemption for variable APR changes that follow an index movement created a structural incentive for issuers to convert to variable APR products. A variable APR can rise as the prime rate rises without triggering any of the Act’s rate-change restrictions, because the issuer is not the proximate cause of the change. Within a few years of the Act taking effect, fixed APR credit cards had largely disappeared from the major bank product lineups.
What “fixed” usually means today on a credit card
Where the word “fixed” still appears on credit card marketing today, it usually refers to one of two scenarios:
- The intro APR portion of a 0% intro offer is “fixed” at 0% for a specified number of months. This is a fixed rate for that promotional window only. After the intro ends, the rate reverts to the standard variable APR.
- A small number of credit union credit cards still carry true fixed APRs, typically at credit unions that do not publish multi-tier APR ranges. These are the exception, not the rule.
If you see a card marketed as “fixed APR” today, read the cardholder agreement carefully. Many advertisements use the term loosely to mean “not changing in the near term” rather than the regulatory meaning of a fixed rate that does not move with an index.
Practical implications for card choice
Since variable APR is effectively the universal default, the practical decision points are:
- Margin over prime, not absolute rate. What matters is how much your card adds to the prime rate. A card with a 10% margin will be more expensive than a card with a 6% margin in all rate environments.
- Expect changes when the Fed moves. The Federal Reserve publishes its expected rate trajectory in the FOMC summary of economic projections. If the Fed signals more rate hikes, expect your card APR to follow within a couple of statement cycles.
- Credit union APR ceilings provide a hard upper bound. Federal credit unions are capped at 18% by NCUA rules. Even in a high-rate environment, the ceiling holds. See the credit union vs bank pricing guide for more.
- 0% intro APRs are immune to prime rate moves. A 21-month 0% intro APR stays 0% even if the Fed hikes ten times during that period. The reversion APR moves with the prime rate, but the intro rate is fixed for the intro window.
Reader questions
Frequently asked questions
Are there any fixed APR credit cards left?v
A small number of credit union cards still advertise fixed APRs. The vast majority of US consumer credit cards switched to variable APR after the CARD Act of 2009 changed the rules around rate increases. The Federal Reserve and CFPB both treat variable APR as the market default.
Why did the CARD Act effectively kill fixed APR cards?v
The Act restricts when issuers can raise the APR on existing balances. With fixed APR cards, issuers had limited ability to recover funding cost increases over the long life of an account. Variable APR cards, where the rate moves automatically with the prime rate, sidestep this; the Act’s rate-change restrictions explicitly exempt automatic changes driven by an index movement.
What is the prime rate?v
The prime rate is the interest rate that major US banks charge their most creditworthy commercial customers. It is published in the Wall Street Journal and tracked by the Federal Reserve in the H.15 release. The prime rate is typically the federal funds target rate plus 3 percentage points and moves whenever the Fed adjusts its target.
How quickly does my APR change after a Fed rate move?v
Usually within one to two billing cycles. Most cardholder agreements specify that the APR is recalculated periodically based on the prime rate published on a specific date (often the last day of the month or the first day of each statement period). After a Fed rate change, the new APR appears on the next or second statement.
Can a variable APR go down too?v
Yes. If the prime rate falls, variable card APRs fall too. The 2008 to 2015 period of near-zero federal funds rate produced the lowest US credit card APRs in modern history. The 2022 to 2024 rate hike cycle reversed it.