How To Ruin Your Credit Score (2024)

In June 2022, I had a credit score of 826 — a number that FICO, the U.S. company that issues most of these scores, deemed “exceptional.”

One year later, I had a score of 670 — a 156-point drop, putting me on the brink of “fair,” a euphemism for “think twice before you lend any money to this guy.”

The trigger for this decline wasn’t poverty or irresponsibility, I’m happy to say. It was curiosity.

A credit score is meant to tell lenders how likely you are to repay what you borrow. A score can have a big impact on your expenses and quality of life, influencing the interest you’ll pay on a mortgage or auto loan — or whether you’ll get one at all. It can also affect which homes you can rent and the cost of your car insurance.

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But information about what exactly makes your score rise and fall, and by how much, can be maddeningly vague. FICO (short for Fair Isaac Corporation) lists five variables it uses to calculate scores; 35 percent stems from payment history, for example. But that tells me absolutely nothing about how many points my score will drop if I miss a payment.

Since FICO won’t comment on individual situations, I made a rash decision: The only way to find out what would ruin my credit score was to ruin my credit score. What would move the needle, and how much would the needle move?

Some background: My credit history goes back decades. I don’t have a mortgage. I don’t have a car loan. I pay off my credit card balances monthly, and I haven’t missed a payment in years. I began this test pretty certain that I had no impending transactions that would involve my credit score.

Here’s what I learned.

Lesson 1

I have several different credit scores to ruin.

I knew I had more than one credit score, but I was shocked to find out just how many I have: about 40. One reason is that FICO has several different scoring formulas. The most common is FICO 8, which rates you on a scale from 300 to 850. But there are also older and newer versions of that formula, numbered from 2 to 10T, along with versions specifically tailored to mortgage lenders, auto lenders and credit card issuers.

Another reason I have so many scores is that FICO and VantageScore — a credit-scoring rival of ­FICO’s — each have three separate sources of data: the credit reporting bureaus Equifax, Experian and TransUnion. Those bureaus collect information from lenders about people’s borrowing and payments but don’t calculate scores. Instead, they leave that to FICO and VantageScore, whose formulas can spit out different numbers depending on the data that’s fed into them. So I had three different FICO 8 scores to track: 810 based on TransUnion data, 822 from Equifax and 826 from Experian. The VantageScore version I began following, drawn from TransUnion, was 811.

Lesson 2

Focus on ranges, not points.

Soon after I first peeked at my scores, my VantageScore dropped 7 points, to 804. The reason: I was now using 8 percent of my available credit, up from 4 percent the week before, doubling what’s known as my utilization rate. My total debt — the credit card bills I had yet to pay — had jumped to $3,371. One of my FICO scores dropped 10 points; another dropped 4. A few weeks later, after I paid off one of my cards, two of my FICO scores rose 3 points; the third rose 8.