Good Debt vs Bad Debt -

Understanding When Debt Helps — and When It Hurts

Debt is neither inherently good nor bad. What matters is what it is used for — and whether the financial outcome justifies the cost of borrowing.

Why the Distinction Matters

Most people are taught to avoid debt entirely. But this perspective oversimplifies a more nuanced reality.

Some forms of debt can genuinely improve your financial position over time. Others erode it steadily. Understanding the difference allows you to make more informed decisions about when borrowing makes sense — and when it does not.

What Makes Debt “Good”

Good debt is used to acquire something that has the potential to generate future value — either through income, appreciation, or improved earning capacity.

Common examples include:

Education — borrowing to fund a qualification that leads to meaningfully higher income can be a sound financial decision, provided the cost of the debt is proportionate to the expected return.

Business investment — debt used to start or grow a business that generates profit can create long-term financial value.

Property — in some circumstances, a mortgage used to purchase property that appreciates in value or generates rental income may be considered productive debt.

The key question with any debt is whether the expected return exceeds the cost of borrowing. If the answer is yes — and the risk is manageable — the debt may be justified.

What Makes Debt “Bad”

Bad debt is used to fund consumption or purchase assets that decline in value over time.

Common examples include:

High-interest consumer credit — credit card balances carrying 18–25% annual interest rates grow quickly and offer no financial return.

Loans for depreciating assets — financing a new vehicle, electronics, or lifestyle purchases through high-interest credit means paying significantly more than the item is worth — for something that loses value immediately.

Lifestyle debt — borrowing to fund spending beyond your means creates an ongoing cost with no productive return.

The defining characteristic of bad debt is that it makes you poorer over time — both through the interest paid and through the opportunity cost of money that could have been saved or invested.

The Mathematics of High-Interest Debt

The cost of high-interest debt is often underestimated.

Consider 100,000 THB of debt at 18% annual interest:

Annual interest cost:   18,000 THB per year

Compare this to 100,000 THB invested at 6% per year:

Annual investment return:   6,000 THB per year

The negative effect of high-interest debt is three times greater than the positive effect of investing at a typical long-term return. This is why addressing high-interest debt before investing is generally the more rational financial decision.

When Debt Becomes Problematic

Debt becomes financially dangerous when:

Interest rates are high relative to any potential return
Repayments consume a large portion of monthly income, limiting flexibility
The debt is used for consumption rather than value creation
Multiple debts accumulate simultaneously, making repayment difficult to manage

The goal is not necessarily to be debt-free — it is to ensure that any debt you carry is manageable, purposeful, and working in your favour rather than against you.

Key Takeaways

Debt is not inherently negative — the purpose and cost determine whether it is beneficial
Good debt is used for assets or investments that generate future value or income
Bad debt funds consumption or depreciating assets at a high interest cost
High-interest debt — such as credit card balances — typically costs more than investing can return
Addressing high-interest debt before investing is usually the more effective financial decision

Frequently Asked Questions

Should I pay off all debt before investing?
Not necessarily. Low-interest debt — such as a mortgage at 3–4% — may not need to be fully repaid before investing, as long-term investment returns may exceed the borrowing cost. High-interest debt should generally be prioritised first.

Is a mortgage good debt or bad debt?
It depends on the circumstances. A mortgage used to purchase property that appreciates in value or generates income can be productive debt. However, borrowing more than is manageable — or purchasing in a market that declines — can make a mortgage harmful. The interest rate, loan terms, and property value all matter.

How do I know if my debt situation is manageable?
A commonly used guideline is that total debt repayments should not exceed 30–35% of monthly net income. If repayments consume a higher proportion, financial flexibility becomes significantly limited.