The "Good Debt vs. Bad Debt" Myth, Reconsidered
Most of us were handed a simple rule early in our financial lives: mortgages and student loans are "good debt," credit cards and car loans are "bad debt." It's a tidy two-column system, and it has the advantage of being easy to remember. The problem is that it can quietly steer households away from decisions that would actually benefit them.
The good/bad label focuses almost entirely on what you bought with the money. A more useful question is: what is this debt costing me, right now, to carry?
Where the Conventional Wisdom Comes From
The "good debt" category was built on a few reasonable observations. Mortgages tend to carry lower interest rates than consumer credit. Student loans have historically been tied to higher lifetime earnings. Both can come with tax considerations (though those vary widely by situation — consult a qualified tax professional for specifics). And both involve assets or outcomes that, at least in theory, appreciate or pay dividends over time.
"Bad debt," meanwhile, usually means high-interest, short-term borrowing used for consumption — things that don't generate a return and cost a lot to carry.
None of that is wrong exactly. But framing debt as inherently good or bad based on its category rather than its actual cost can lead households to underpay high-rate mortgage balances while letting lower-rate consumer debt slide, or to feel virtuous about carrying a large mortgage simply because it's "the right kind."
The Cost of Carry Is What Actually Matters
In investing, "cost of carry" refers to the ongoing cost of holding a position. The same idea applies to debt: every month you carry a balance, you are paying a real price for that borrowed money. The relevant number isn't the loan category — it's the interest rate (and, to be precise, the annual percentage rate, or APR, which captures fees as well).
Consider two illustrative households:
- Household A has a mortgage at 7.1% and a car loan at 4.9%. By the conventional framework, both are arguably "good" or at least acceptable debt. But the mortgage is actually the more expensive money to carry.
- Household B has a student loan at 5.5% and a credit card at 5.9% (a promotional or older balance-transfer rate). By the conventional label, the credit card is "bad" — but the rate difference is only 0.4 percentage points.
Labeling one debt good and one bad doesn't help either household decide where to direct extra dollars. The rate does.
Opportunity Cost: The Other Side of the Ledger
Cost of carry is only half the picture. The other half is opportunity cost — what else could those dollars do?
Every extra dollar you put toward a debt earns you a guaranteed, risk-free return equal to that debt's interest rate. You eliminate $1 of balance that would have compounded against you. That "return" is certain in a way that market returns are not.
So the real question becomes: is there something else my money could do that meaningfully exceeds my debt's cost of carry, after accounting for risk?
For many households, an emergency fund with three to six months of expenses is a clear priority before accelerating any debt payoff — because going into higher-rate debt to cover a surprise can be far more costly. Beyond that, employer-matched retirement contributions are often worth capturing because the match itself represents an immediate return that is hard to beat. But those are general frameworks, not personal prescriptions. Every household's numbers and circumstances are different.
The point is that thinking in terms of cost of carry and opportunity cost gives you actual numbers to compare — not just comforting labels.
"Good Debt" Can Still Become a Problem
A mortgage at 3% in 2021 had a very different cost of carry than a mortgage originated at 7% in 2024. The same loan type, wildly different math. Meanwhile, a household carrying that low-rate mortgage and simultaneously holding high-yield savings or short-term bonds earning more than 3% was, in a real sense, being paid to carry the debt. That dynamic reverses completely at higher rates.
The label "good debt" doesn't update with market conditions. Your actual interest rate does.
There's also a behavioral dimension worth naming: the good/bad framing can encourage people to ignore debts in the "good" category for years — assuming they don't need attention. But any debt you carry has a payoff date, and compressing that date through intentional extra payments can meaningfully reduce total interest paid over the life of the loan, regardless of whether the loan is a mortgage or a medical bill.
A More Useful Framework
Instead of sorting debts into good and bad buckets, try looking at them through three lenses:
- Rate — What is the APR? Higher rates cost more and generally deserve more urgent attention.
- Balance and term — A large balance compounds more aggressively than a small one. How long until each debt is gone at the current pace?
- Flexibility — Some debts (like a mortgage) are secured and structured; others have minimum payments that fluctuate. Knowing which debts give you flexibility to pay more without penalty matters.
Tools like Debt|Done|Date. are built around exactly this kind of visibility — showing you not just what you owe, but when each debt ends and how different payment choices change that timeline. Mapping your debts by rate, balance, and payoff date puts real numbers on the table instead of reassuring (but potentially misleading) categories.
The goal isn't to feel bad about any particular debt you're carrying. It's to see each one clearly, understand what it's costing you each month, and make intentional choices from there. That kind of clarity is more useful than any two-column label system ever could be.
Debt|Done|Date. publishes this article for general education only. It is not financial, legal, tax, or investment advice, and it is not a recommendation of any specific product, lender, or strategy. Mortgage acceleration involves voluntary extra principal payments — there is no guaranteed payoff date or savings amount. Your situation is unique; consult a licensed professional before acting. Individual results vary.