Debt and Credit, Decoded

Not all debt is equally bad. The difference matters because it determines what to attack first and what to merely manage.

The two flavors of debt

Productive debt tends to be lower-interest, used to buy something with long-term value (a house, an education that genuinely raises lifetime earnings) or both. Mortgages at 6%, federal student loans at moderate rates, low-rate auto loans. Manage it. Don’t panic about it.

Expensive debt tends to be high-interest and tied to consumption that has already happened. Credit-card balances at 20-28% APR, payday loans, store-card “buy now pay later” that turned into 30% APR after the promotional period. This is the debt that quietly eats people’s financial lives.

The line between “manage” and “attack” is roughly 8-10% interest. Above that, it makes mathematical sense to pay it off as fast as possible. Below that, you can usually afford to pay the minimum on schedule and put extra money into investing or savings instead.

Why credit-card interest is so destructive

A 22% APR credit card looks like “22% per year.” In practice it compounds monthly, which means your effective annual rate is closer to 24.4%. And because it compounds on a balance you carry every month, the math gets ugly fast.

Concrete example: $5,000 balance at 22%, paying only the minimum (typically 2-3% of balance):

• Years to pay off: roughly 22 years
• Total interest paid: ~$8,000 (more than the original balance)

That same $5,000 paid off at $250/month:

• Years to pay off: ~2 years
• Total interest paid: ~$1,200

The minimum payment is the bank’s strategy, not yours. If you have credit-card debt, paying anything above the minimum is one of the highest-return moves you can make. Eliminating a 22% liability is mathematically equivalent to earning a 22% return. Guaranteed and tax-free.

The two payoff strategies

Two methods, both legitimate, both with the same destination:

Avalanche method: List all your debts. Pay the minimums on everything. Throw any extra money at the debt with the highest interest rate. When that one is dead, roll its payment into the next-highest-rate debt. Mathematically optimal: minimizes total interest paid.

Snowball method: Same setup, but throw extra money at the debt with the smallest balance first, regardless of rate. Mathematically slightly worse, but the early wins create real psychological momentum. People who try and fail at avalanche often succeed at snowball.

The right method is the one you will actually finish. For most people with several debts, the difference in total interest is a few hundred dollars over a few years, small compared to the difference between finishing and giving up.

Credit scores in 60 seconds

Your credit score is a 300-850 number that estimates how likely you are to repay borrowed money. Lenders use it to decide whether to approve you and what interest rate to charge.

The five factors and roughly how much each matters:

• Payment history (~35%). Whether you pay on time. By far the biggest factor. One late payment can drop your score 50+ points.
• Amounts owed / utilization (~30%). How much of your available credit you are using. Keeping credit-card utilization under ~30% (and ideally under 10%) helps a lot.
• Length of credit history (~15%). How long your accounts have been open. Why closing your oldest credit card can hurt.
• Credit mix (~10%). Whether you have a mix of revolving (cards) and installment (loans) credit. Don’t over-engineer this.
• New credit (~10%). Recent applications. Several applications in a short window dings the score temporarily.

Things that do not directly affect your credit score: your income, your savings, your investments, your job, your debit-card usage, or how much money is in your bank account. The score is purely about how you handle borrowed money.

The simplest credit-building habit

If you have a credit card: use it for one or two recurring expenses you would already pay (gas, a streaming service). Set up automatic full-balance payments every month. You build payment history, you keep utilization low, and you never pay a cent of interest. That is the unglamorous version of “building credit” and it works for almost everyone.

Tomorrow we close out the week with investing: how compounding actually works, what an index fund is, and why “just start” is most of the game.