The question comes up constantly: I have $500 extra this month. Should I throw it at my credit card or put it in my Roth IRA?
The honest answer is that most personal finance advice on this topic gives you a rule when you actually need a number. Here’s how to get the number.
The core comparison
Every debt you carry has an interest rate. Every investment has an expected return. The decision reduces to which number is higher.
If your credit card charges 22% APR and your investment account returns 10% historically, paying off the card gives you a guaranteed 22% return the moment you do it. No market volatility, no sequence-of-returns risk, just a certain 22%. That beats a probable 10%.
If your mortgage is at 3.5% and your investment account returns 10%, the math runs the other direction. Keeping the cheap debt and investing the extra cash creates a 6.5-point spread in your favor over time.
The line where the decision flips is roughly 6-7%, approximately the long-run real return of a diversified equity portfolio after inflation. Debt above that line: pay it first. Debt below that line: invest while making minimum payments.
When the math says pay off debt
Credit cards are the clearest case. The average credit card APR in 2026 runs around 20-22%. No investment reliably beats that guaranteed return. Every extra dollar toward a 22% card is a risk-free 22% return. The math is unambiguous.
High-rate personal loans (anything above 12-14%) fall in the same category. Use the debt consolidation calculator to see if you can first bring the rate down through consolidation, then accelerate payoff.
Student loans at variable rates that have crept above 8-10% are increasingly in “pay first” territory, especially in a rate environment where returns on conservative investments are modest.
The emotional case for paying off debt matters too. The calculator can’t quantify the cognitive overhead of carrying debt, the background stress, the constraints it puts on job choices and risk tolerance. For many people, being debt-free changes their financial behavior in ways that compound over years. That’s worth something the spreadsheet doesn’t capture.
When the math says invest first
A mortgage at 3-4% (if you have one from 2020-2021) is the textbook case for “invest, don’t prepay.” At 4%, every dollar you put toward principal is returning 4% guaranteed, but a broad market index historically returns 10% nominal, 7% real. Keeping the cheap debt and investing the spread generates meaningful wealth over a 20-30 year horizon.
Employer 401(k) match is an exception that overrides almost any other calculation. If your employer matches 50% or 100% of your contribution, that’s an instant 50-100% return before any market movement. Capture the full match before paying anything extra on debt, regardless of interest rate. It’s the clearest free money in personal finance.
Roth IRA contributions have one feature that changes the calculus slightly: you can withdraw your contributions (not earnings) at any time without penalty. That means a funded Roth isn’t completely illiquid. It’s a hybrid between investment and emergency backup. If your emergency fund is thin, maxing a Roth while carrying modest-rate debt (7-9%) is defensible.
The middle cases
The 7-12% range is genuinely ambiguous, and anyone telling you there’s a clear answer there is oversimplifying.
A student loan at 8% in 2026, a personal loan at 9%, a car loan at 10%: these don’t have a clean answer because the future return on your investments isn’t certain. If markets return 12% over the next decade, you’d have been better off investing. If they return 5%, you’d have been better off paying down the 8% loan.
What most financial planners recommend in this range: split the extra dollar. Put half toward the debt, half toward the investment account. You hedge the uncertainty, maintain momentum on debt payoff, and don’t sacrifice years of compound growth on the investment side.
The order that makes sense for most people
Given all of the above, here’s a sequence that holds up across most situations:
Step 1: Emergency fund first, 3 months of expenses in a high-yield savings account earning 4-5%. Without this, any unexpected expense sends you back to high-rate debt.
Step 2: Capture any 401(k) employer match. This is a 50-100% instant return and nothing beats it.
Step 3: Pay off high-rate debt (credit cards, personal loans above 10%). Use the debt consolidation calculator to see if you can first reduce the rate through consolidation, then accelerate payoff.
Step 4: Max your Roth IRA ($7,000/year in 2026) if you’re eligible. Tax-free compounding over decades is worth prioritizing over moderate-rate debt.
Step 5: Return to debt vs. invest for anything remaining. Mortgage, low-rate student loans, 7-9% personal loans: this is where the math genuinely depends on your return assumptions and timeline.
What changes the answer
A few things shift this calculation meaningfully:
Your risk tolerance. If you’d sleep better debt-free even with mathematically suboptimal returns, that’s a valid input. Personal finance is personal.
Time horizon. A 25-year-old has 40 years of compounding ahead. The earlier you start investing, the more the time advantage matters, even against moderately high debt.
Job security. High debt load plus uncertain income is a dangerous combination. If your job situation is unstable, reducing debt payments may be more valuable than investment upside. Less fixed monthly obligation means more resilience.
Tax situation. Mortgage interest (if you itemize) is partially tax-deductible, which effectively lowers the rate. A 6% mortgage in the 22% tax bracket is closer to a 4.7% effective rate, well below the “pay it off” threshold.
The number to run
If you want a clean answer for your specific situation: take your highest-rate debt and compare it to 7%. Above 7%: prioritize payoff. Below 7%: prioritize investing. Between 5-9%: split or apply the sequence above.
Then run the debt consolidation calculator to see if bringing that rate down through consolidation changes the equation. Sometimes the answer isn’t “pay off vs. invest,” it’s “restructure first, then both.”
→ Debt Consolidation Calculator: see if consolidating changes your payoff math
Frequently Asked Questions
Is it better to pay off debt or save for retirement?
Capture the full employer 401(k) match first. That’s a guaranteed 50-100% return that beats everything else. After that, pay off high-rate debt (above 8-10%) before contributing beyond the match. Once high-rate debt is gone, prioritize Roth IRA contributions before additional debt payoff on lower-rate balances.
What interest rate is the cutoff for investing vs. paying off debt?
The commonly cited threshold is 6-7%, approximating long-run real market returns. Above that: pay off the debt (the guaranteed return beats probable investment returns). Below that: invest while making minimums. In the 6-10% range, splitting the difference is reasonable because future returns are uncertain.
Should I pay off my mortgage early or invest the extra?
For mortgages at 3-5% (common from 2020-2022): invest the extra, strongly. The expected long-run market return (7-10%) significantly exceeds the guaranteed 3-5% from mortgage paydown. For mortgages at 6.5-7.5% (2023-2026 originations): the gap narrows substantially, and paying down the mortgage carries no sequence-of-returns risk. Most planners in 2026 treat 6%+ mortgages as worth actively paying down alongside investing.
Worth It Calculators provides educational tools and general information. I’m not a licensed financial advisor. Always review your full financial picture before making debt payoff or investment decisions. Some links may earn a commission at no extra cost to you.