Should You Pay Off Debt or Invest? The 6–7% Rule
"Should I pay off debt or invest?" has a cleaner answer than most people expect, and it hinges almost entirely on one number: the interest rate on the debt.
The one exception that comes first: the employer match
Before any debt payoff beyond minimums, capture your full employer 401(k) match. A 100% match on your first few percent of salary is a guaranteed, immediate doubling of that money — it beats paying off even a 24% credit card. Always grab the match first.
The 6–7% rule
After the match, compare the debt's APR to what you could reasonably earn investing. The stock market has historically returned about 7–10% per year — but that's before taxes and inflation, and it's volatile and not guaranteed. Paying off debt is a guaranteed, tax-free return equal to its rate.
- Above ~7% APR (credit cards, personal loans, some private student loans): pay it off before investing more. You almost certainly can't out-earn it reliably.
- Below ~5% APR (most mortgages, subsidized student loans, low auto loans): invest alongside minimum payments — your expected after-tax return is higher.
- The 5–7% gray zone: a personal call. Guaranteed payoff vs. likely-but-risky market returns. Risk-averse? Pay it down. Comfortable with volatility? Invest.
Use the avalanche method
When attacking debt, the mathematically optimal approach is the avalanche: pay minimums on everything, then throw every spare dollar at the highest-APR balance until it's gone, then roll that entire payment to the next-highest. It minimizes total interest paid.
The snowball method (smallest balance first) costs slightly more in interest but delivers quick psychological wins. If motivation is your bottleneck, snowball; if you want the lowest cost, avalanche.
Why high-interest debt is so dangerous
A $5,000 balance at 22% APR costs $1,100 a year in interest — money that buys you nothing. Carrying it while investing means you're effectively borrowing at 22% to earn ~7%. That math never works over time.
What about mortgages?
A mortgage is usually low-rate, and part of every payment is principal that builds equity — it's not pure expense. At today's rates many people invest rather than prepay, though paying it off before retirement is a valid, lower-risk choice. See your full picture in FinFire's roadmap.
Frequently asked questions
- Should I pay off debt or invest?
- Capture any full employer 401(k) match first. Then pay off debt above roughly 6–7% APR before investing more, since that beats likely after-tax market returns. Invest alongside minimum payments on debt below about 5%.
- Is the debt avalanche or snowball better?
- The avalanche (highest interest rate first) minimizes total interest paid and is mathematically optimal. The snowball (smallest balance first) costs a bit more but gives faster motivational wins.
- Should I pay off my mortgage early?
- Mortgages are typically low-rate and partly build equity, so many people invest instead of prepaying. Paying it off before retirement is still a reasonable, lower-risk choice — it depends on your rate and risk tolerance.