Good debt funds assets that grow or produce income at an interest rate lower than the expected return. Bad debt funds consumption at high rates with no return. While the category matters, what matters more is whether the math works for your income, discipline, and circumstances.
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The Framework
"Good debt" and "bad debt" aren't moral categories. They're financial categories based on:1
- Interest rate you pay
- Asset value (appreciating or depreciating)
- Expected return on the asset
A mortgage at 6% on an appreciating asset (a house) that you could never otherwise afford is good debt. A credit card at 20% for a depreciating asset (clothes) is bad debt.
But the framework is more nuanced than "house = good, credit card = bad."
Good Debt
Characteristics:
- Low interest rate (below 7%)
- Appreciating or income-producing asset
- Builds equity over time
- Tax-deductible interest (in some cases)
Examples:
Mortgage (4–7% interest): You borrow $400,000 to buy a $500,000 home. Homes appreciate 3–4% annually historically.2 You build equity with each payment (principal goes toward ownership). Mortgage interest is tax-deductible (if you itemize). This is leverage applied to an appreciating asset.
Comparison: Renting at $2,500/month builds no equity, and rent only increases. A $400,000 mortgage at 6% costs $2,400/month but builds equity. In 30 years, the home might be worth $1.3 million and you own it outright.
Student loans (4–8% interest): You borrow $50,000 to earn a degree that pays $65,000/year vs. $40,000 without it. Over 40 years, the earnings premium is $1 million or more.3 A $50,000 debt to access a $1 million earnings advantage is good debt.
Caveats: Only if the degree leads to higher income. A $100,000 degree that doesn't improve earnings is bad debt. A $20,000 degree that leads to $70,000/year is good debt.
Home equity line of credit at 7% used to renovate your home: You borrow against your home's equity to make improvements that increase value. A $50,000 kitchen renovation on a $500,000 home might increase its value to $530,000. Leverage applied to adding value.
Caveats: Only if renovations actually add value. Luxury renovations that don't increase resale value are bad debt applications.
Business loan at 6–8%: You borrow to start a business expected to generate 15–20% returns. Leverage applied to a high-return investment.
Caveats: Only if the business actually generates returns. A failing business funded by debt is bad debt.
Bad Debt
Characteristics:
- High interest rate (above 10%, typically 15–25%)
- Depreciating asset (or no asset at all)
- Consumes income without building equity
- Often used for lifestyle, not investment
Examples:
Credit card debt at 20% for consumption: You borrow $5,000 to buy clothes, electronics, or dining. The items depreciate immediately. You pay $1,000 or more per year in interest on a purchase that brought no return.4
This is leverage applied to depreciating consumption. It's wealth destruction.
Payday loans at 400% APR: You borrow $300 and pay back $345 in two weeks. Annualized, that's 400% or more in interest.6 You're paying to access your own future paycheck.
This is exclusively bad debt.
Auto loan at 12% on a depreciating car: A new car loses 20% of value in year one. You borrow $30,000 at 12% (total payment $7,020/year) for an asset that's worth $24,000 immediately. You're underwater from the start.5
A $5,000 used car at 0% (paid cash) is better; a $30,000 new car at 12% is leverage applied to a depreciating asset.
"Buy now, pay later" at 0% for non-essential purchases: Appears 0%, but typically requires on-time payments. One miss and you face late fees. It enables overspending.
Technically 0%, but bad debt in behavior: it encourages spending beyond your means.
The Personal Lens: When Good Debt Is Bad for YOU
The framework isn't universal. Good debt can become bad depending on your discipline.
Example 1: The mortgage you can't afford
Your gross income is $80,000. You qualify for a $400,000 mortgage ($2,400/month). This pushes your debt-to-income (DTI) ratio to 48% (your maximum).
Theoretically, a mortgage is "good debt." But for you, it's financially dangerous. You have no cushion. One medical crisis, one job loss, and you're in foreclosure.
For you, a $250,000 mortgage (40% of income) is good debt; a $400,000 mortgage is bad debt despite being theoretically "good."
Example 2: The low-interest loan you can't discipline
You borrow $5,000 at 0% for a "business investment" you're unsure about. Theoretically good (low rate, potential return).
But you also have a history of overspending and never executing on plans. The 0% doesn't matter if the business fails and you're left with $5,000 in debt.
For you, avoiding the debt and saving first is better than borrowing cheap for an uncertain investment.
The Key Question: Expected Return
The line between good and bad debt is:
Expected return on the asset > Interest rate on the debt
Mortgage at 6% on an asset appreciating 3–4% annually is borderline; the math is close. But you also get:
- Housing you need anyway (avoiding rent)
- Equity building
- Tax deductions (potentially)
- Forced savings mechanism (mortgage payments)
So a 6% mortgage is still "good" despite close math.
A credit card at 20% for clothes (0% appreciation, immediate depreciation) is clearly bad: -20% vs. 0% is terrible math.
The Strategic Use of Good Debt
Wealthy people use good debt strategically to accelerate wealth:
Scenario: You have $100,000 saved. You can either:
- Put it all down on a home (no mortgage)
- Put 20% down ($20,000) and mortgage $80,000 at 5%
If real estate appreciates 3%/year and mortgage costs 5%/year, why mortgage?
Because you still have $80,000 liquid. If you invest it at 8% returns in the stock market, you earn $6,400/year on that capital. Your mortgage costs $4,000/year. Net gain: $2,400/year.
Over 30 years, this leverage strategy can double your wealth compared to paying cash.
The caveat: This requires discipline (actually invest the remaining capital, don't spend it) and income stability (you must pay the mortgage even if investments underperform).
How to Tell the Difference
Before taking on any debt, ask:
- What am I borrowing for? (Asset, consumption, lifestyle?)
- What's the interest rate? (Below or above reasonable market returns?)
- Does the asset appreciate or depreciate? (Or produce income?)
- What's my expected return vs. the borrowing cost? (Return > interest rate?)
- Can I afford this if my income changes? (Is my DTI sustainable?)
- Do I have the discipline to stick to the plan? (Will I actually invest the capital, not spend it?)
If answers are good, it's likely good debt. If you have doubts, it's probably bad debt.
A Worked Example
Scenario: Should you borrow $25,000 for an MBA?
Analysis:
- Borrowing for: Education (asset that produces income)
- Interest rate: 5% (student loan)
- Expected return: Degree increases salary from $60K to $80K (+$20K/year, a 33% raise)
- Payoff: $25,000 debt at 5% = $265/month. Additional income: $1,667/month. Net: +$1,402/month
- Sustainability: 5 years to pay off debt; income increase is permanent
- Discipline: Assuming the degree leads to the higher-paying job
Verdict: Good debt. The expected return ($1.4M or more in additional lifetime earnings) far exceeds the cost ($25,000 plus interest).
Alternative scenario: Should you borrow $25,000 for luxury items you want?
- Borrowing for: Consumption
- Interest rate: 18% (credit card)
- Expected return: $0 (items depreciate)
- Payoff: $25,000 debt at 18% = $375/month interest alone. No income to offset.
- Sustainability: Years of payments for temporary enjoyment
- Discipline: High risk of not being able to pay off
Verdict: Bad debt. The cost ($25,000 plus $7,000 or more in interest) far exceeds the value ($0; items worth $5,000 in 5 years).
The Bottom Line
Good debt accelerates wealth building. Bad debt destroys it. The difference is whether the borrowed money generates a return that exceeds the cost of borrowing.
Use good debt strategically. Avoid bad debt entirely. And be honest with yourself: is this debt good for you given your discipline and circumstances?
