Pay Off Debt vs Invest

Both paths deploy exactly the same cash every month: your minimum payment plus the extra amount you have available. What differs is where it goes. In the debt-first path, all of it goes to the debt until the balance is gone; after that, the entire amount is invested for the rest of your horizon. In the invest-first path, only the minimum goes to the debt, and everything else is invested — including the minimum payment itself once the debt is finally cleared, since that money is no longer needed.

Interest on the debt accrues monthly, and investments compound monthly at your expected return. At the end of the horizon the tool compares net worth: investments minus any debt still outstanding. The chart shows how each path's net worth evolves year by year.

The defaults are a $5,200 debt at 16%, a $156 minimum payment, $104 a month extra, a 12% investment return and a 5-year horizon. Debt-first clears the balance in month 24 and finishes with about $11,417; invest-first ends with about $11,117. Debt-first is ahead by roughly $299 — a 2.6% difference, which the tool labels a close call.

It's a close call because the two rates are close: a guaranteed 16% saved by clearing the debt against an expected, not guaranteed, 12% from investing. When the rates are this near each other, the gap is small and the sensible choice depends more on your appetite for risk than on the arithmetic.

The break-even is simple. Paying off debt is a guaranteed return equal to its interest rate. Investing earns an expected return that isn't guaranteed. So the verdict flips exactly where the two rates meet: with a 12% investment return, that's a debt rate of 12%; with a 16% debt rate, it's an investment return of 16%.

The tool compounds a smooth 12%, but real investment returns arrive unevenly, and a five-year stretch can fall well short of any expected return. The interest you save by clearing a debt can't have a bad year. That's why, even when investing edges ahead on paper, someone who would be uncomfortable holding a loan while markets fall may reasonably choose debt-first — and why a credit card at 30–40% should almost never wait for an investment to beat it.

A useful rule of thumb: treat your debt's rate as the return you're comparing against. If you can't confidently expect to beat it after risk and tax, clear the debt.

• Tax. Interest on some loans, such as education or home loans, may be deductible, which lowers the debt's effective rate; gains on investments may be taxed, which lowers their effective return.
• Prepayment fees or penalties some lenders charge for paying a loan off early.
• Variable interest rates. The debt rate is assumed constant, while many loans and all credit cards can change.
• Employer matching and other free money. A match on retirement contributions is an instant return that usually beats both options here.
• Liquidity. Cash sent to a lender is gone, while invested money can be reached in an emergency — which is why an emergency fund should come before either.
• The peace of mind of being debt-free, which is worth something the numbers don't try to price.

• Debt Payoff Strategy Planner — if you have several debts, compare snowball and avalanche across all of them
• Debt Management — how to think about which debt to attack first
• Emergency Funds — why a cash buffer comes before paying down or investing
• Compound Interest — why debt and investments both grow faster than they look
• SIP Calculator — the invest side — see what a monthly amount grows to at the return you assume
• Emergency Fund Calculator — work out how many months of cash to hold before you commit to either path