Good Debt vs. Bad Debt: A Decision Framework

# Good Debt vs. Bad Debt: A Decision Framework

"Good debt" and "bad debt" are the most oversimplified labels in personal finance. The standard version — mortgages are good, credit cards are bad — captures something real but misses the nuance that actually matters for decisions.

A more useful framework asks three questions about any debt: Does it fund an asset that appreciates or generates income? Is the interest rate reasonable relative to expected returns? And will the payment be sustainable under realistic income scenarios?

**Mortgage debt** is called good debt because real estate has historically appreciated and mortgage rates are generally lower than other consumer debt. This holds when: the home is in a stable or growing market, you plan to stay long enough to recover transaction costs, and the mortgage payment does not crowd out savings and investing. A mortgage on an overpriced home with a payment that absorbs 45% of income is not good debt by any real definition.

**Student loan debt** is called good debt because education increases earning potential. This holds when: the degree leads to a career with income meaningfully above what you would have earned otherwise, and the loan balance is proportionate to that expected income. A $180,000 law school debt for a public defender role at $65,000 is not good debt by any useful standard.

**Business debt** funds assets or operations that generate returns. When the expected return on the investment exceeds the cost of borrowing, the math is favorable. When the business fails, all debt is bad debt.

**Credit card debt** is called bad debt primarily because of the rate — 20–28% APR on consumer goods that depreciate immediately. There is no investment thesis. The money was spent on consumption.

**Auto loan debt** is in between: the rate is usually lower than credit cards, but the asset depreciates. It is a necessary cost for most people, not an investment.

Use the framework below for any debt you are considering or already carry.

The "good debt" label is doing too much work. What actually matters is the spread between your borrowing rate and your expected return on the alternative use of that money.

A mortgage at 3% (when those rates existed) while investing at historical equity returns of 7–10% was genuinely favorable. The same mortgage at 7.5% in a slower appreciation market narrows that spread considerably.

Student debt at 4.5% federal rates for a degree that adds $30,000/year to income has a favorable spread. Private student loans at 11% for a degree with uncertain ROI do not.

Debt carries a non-financial weight that pure rate calculations ignore. The anxiety of owing money, the constraints it places on career risk-taking (hard to leave a job when a mortgage payment depends on it), and the impact on relationship dynamics are real costs that don't appear in an amortization table.

For high-rate consumer debt especially, the behavioral cost of staying in debt — the stress, the constraint, the compounding — often exceeds the mathematical cost. This is not irrational. It is a legitimate preference that the "optimize the math" framework misses.

Pay off debt when: the rate is above 6–7%, the debt funds depreciating consumption, or the payment meaningfully constrains your life choices. Consider keeping debt (or investing instead of paying extra) when: the rate is below 5%, the debt funds an appreciating asset, and the payment is comfortable relative to income.

The gray zone — 5–7% rates — is genuinely a personal decision where both choices are defensible.

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*Related: [Pay off debt or invest?](./pay-off-debt-or-invest) builds the full comparison with compounding math. [Debt-to-income ratio](./debt-to-income-ratio) shows how lenders evaluate your total debt picture.*