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Should I pay off a debt or invest?
Paying down a loan is a guaranteed return equal to its interest rate. Investing might do better — or might not. Compare both after tax, and see how much of the answer rests on an assumption.
The debt
LOANThis decides whether any of the interest is deductible.
The amount you'd either prepay or invest.
Around nine in ten filers take the standard deduction and get nothing back for mortgage interest. For 2026 it is $32,200 married filing jointly and $16,100 single, and the deduction only helps to the extent your total itemized deductions clear that bar.
The investment alternative
MARKETUse 0 for a 401(k), IRA, or other tax-sheltered account. This is charged as an annual drag, which overstates the cost for a buy-and-hold investor — if you expect to defer capital gains for decades, enter something below your marginal capital gains rate.
Enter a balance, rate, years remaining, and the extra amount you have available each month.
All four happen in your browser. Your figures are not sent anywhere — the email opens in your own mail app, already filled in.
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