New Credit

New credit is one of the five categories Fair Isaac Corporation uses to organize what goes into a FICO Score, and the company states its weight plainly: "New credit makes up 10% of a FICO® Score." The category reads recency. Fair Isaac names three inputs: "How many new accounts you have," which it says its scores "look at ... by type of account"; "How many recent inquiries you have"; and "How long it's been since you opened a new account," which it describes as the age of the most recently opened account.

Two things about that list are worth separating at the outset. The middle input, inquiries, has its own mechanics, its own two clocks, and its own rate-shopping rules, and those belong to the hard inquiry page rather than here. The other two are unowned anywhere else, and the more interesting property of the category is not any of the three inputs but what happens around them: opening credit registers in this category and in several others at the same time, which is why the effect of a single new account is harder to predict than a 10 percent weight suggests.

Fair Isaac is describing a pace, not a prohibition. Its own framing is that "People tend to have more credit today and shop for new credit more frequently than ever," and that its scores reflect that reality; the risk signal it names is "opening several new credit accounts in a short period of time," which it says "represents greater risk, especially for people who don't have a long credit history." So the category is not a penalty on borrowing. It is a reading of how fast someone is adding obligations relative to the record already on file.

"By type of account" is the phrase people skip. Fair Isaac writes that its scores "look at how many new accounts you have by type of account," and that they "may also look at how many of your accounts are new accounts." Two readings follow. A count of new accounts is not read against a single threshold across all products; it is read within kinds. And the second clause is a ratio rather than a count, which is why the same two new accounts can read differently on a file with three accounts than on a file with thirty. Fair Isaac does not publish what those numbers are, and no figure should be attached to either clause.

The third input is the newest account's age, and it is a clock that runs on its own. Fair Isaac describes it as "the age of your most recently opened account" and says its scores "may consider the time that has passed since you opened a new credit account, for specific types of accounts." That is a different measurement from the count. A file with one account opened last month reads differently from a file with one account opened three years ago even though both contain exactly one recently added account in the ordinary sense of the phrase.

The part worth carrying away is the cross-factor arithmetic, because it is where the ordinary advice about new accounts actually comes from. Fair Isaac sets out three separate effects on its own page, and they do not point the same way.

Opening an account lowers the average age of the accounts on file, which is the length-of-credit-history category rather than this one. Fair Isaac's caution attaches to circumstance rather than to the act: "New accounts will lower your average account age, which will have a larger effect on your FICO Scores if you don't have a lot of other credit information." The arithmetic of that average is worked on the length of credit history page.

Opening an account and then using it "will increase the 'amounts owed' factor," because the balance rises against the limits. Opening one and not using it does the opposite: Fair Isaac's own example is that if you "open a new credit card account (which could initially lower your score) and then don't use that card for any new purchases," then "over time, this can lower your credit utilization which could mean an increase in your credit score."

And if the new account is a kind you did not previously have, Fair Isaac says it "can increase the 'credit mix' factor," which is a fourth category again.

So one action lands in four places with three different signs, and the net result depends on the file it lands on. That is the honest answer to "will opening a card hurt my score," and it is more useful than a number, because the number that gets quoted, 10 percent, is the weight of the smallest of the four categories involved.

A limit on all of this that belongs on the page. Every weight Fair Isaac publishes is a description of the general population rather than a formula. The company says so about its own chart, and the same caveat governs anything written here: the categories describe what a model reads, not how much any particular file will move.

A lender reports a newly opened account to one or more of the nationwide credit bureaus with its opening date. A scoring model reads that date twice over: once as a count of recent accounts within its kind, and once as the age of the newest account on the file. The same account is simultaneously read by the length-of-credit-history category as a new entry in the average, by the amounts-owed category as an added credit limit and any balance on it, and, if it is a kind of account the file did not previously carry, by the credit-mix category.

A hypothetical example of the limb Fair Isaac describes as the upside, kept in dollars so it can be checked. Marcus has one credit card with a $3,000 limit and a $1,200 balance, so $1,200 ÷ $3,000 = 40% of his available revolving credit is in use. He opens a second card with a $2,500 limit and makes no purchases on it. His debt has not changed, but his available credit has: $3,000 + $2,500 = $5,500, and $1,200 ÷ $5,500 ≈ 21.8%. The same $1,200 now reads as roughly 22 percent rather than 40.

Three things that example does not show, and they are the reason a new account is not a scoring tactic. The new card is now the newest account on the file, so the age-of-newest-account input resets to zero. It enters the average-age calculation at an age of zero, which pulls that average down. And the moment Marcus spends on the second card, the numerator moves with it and the utilization gain shrinks or disappears. Fair Isaac's version of the advice is the plainest one available: "You should carefully consider if you need a new credit account."

Pros

• It is the smallest of the five categories at 10 percent, so a single new account is a small direct input by construction.
• The effect is temporary in the ordinary case, because the newest account stops being the newest as soon as anything is added after it and the average age recovers with elapsed time.
• Adding credit can help on two other fronts at once: an unused limit lowers the share of available credit in use, and a new kind of account can improve the mix.
• Fair Isaac publishes the three inputs, so the category is describable rather than a black box.

Cons

• The effect is largest for the people least able to absorb it. Fair Isaac says a new account has a larger effect on someone without much other credit information, which is the same file that most needs an account.
• Nothing here is quantified. Fair Isaac publishes no threshold for how many new accounts is too many, or how recent is too recent, and any specific number attached to either is somebody's guess.
• Because one account is read by four categories with different signs, its net effect cannot be predicted from the 10 percent weight, and a "will this hurt my score" question has no general answer.
• Opening an account to improve a score inverts the purpose of the account, and Fair Isaac's own guidance on the adjacent credit-mix category is not to open credit for scoring reasons.
• The weights themselves describe the general population rather than any individual file.