Should I pay off my loan early or invest the money instead?
Compare your loan's after-tax interest rate to your expected after-tax investment return. Prepaying a 7% loan is a guaranteed 7% return; an S&P 500 index fund's long-run average is around 7-10% but with volatility and no guarantee. For low-rate mortgages (3-5%), investing typically wins long term; for high-rate debt (credit cards, personal loans above 8%), prepayment almost always wins because the 'return' is risk-free.
Is there a prepayment penalty on my loan?
Check the 'Prepayment' section of your loan agreement. The CFPB's qualified-mortgage rules bar prepayment penalties on most home loans originated after 2014, but auto, personal, student, and some older mortgages can still charge them. Typical penalties are 1-3% of the prepaid amount or a few months of interest. Call your servicer and ask: 'Is there a prepayment penalty if I pay extra toward principal this month?'
Bi-weekly vs monthly: does it actually matter?
Yes — bi-weekly produces 26 half-payments per year, which equals 13 monthly payments, not 12. That extra full payment per year goes entirely to principal. On a 30-year mortgage it shaves roughly 4-5 years off the term. But the benefit only materializes if your servicer applies each bi-weekly payment immediately. If they hold the first half until the second arrives (then apply them as one monthly payment), you save nothing. Many third-party 'bi-weekly programs' charge a fee for what you can do for free by adding 1/12 of the monthly payment to each payment.
Where should I apply extra payments — principal or interest?
Always principal. Interest is already calculated on the balance; you can't 'prepay interest' on a standard loan in any useful way. Reducing principal lowers every future interest charge for the rest of the loan, which is where the savings come from. When you send extra money, include written instructions: 'Apply to principal only. Do not advance the next payment due date.' Many servicers default to advancing the due date, which gives you no interest savings.
Should I prepay my loan or invest in the market instead?
Math says: if your loan's after-tax rate is below your expected investment return, invest. Behaviour says: if debt causes you stress or you might miss future investment contributions, prepay. The 'all of the above' compromise is splitting extra cash: enough prepayment to feel progress, enough investing to capture market growth. For most US households, the practical hierarchy is — (1) capture employer 401(k) match, (2) pay off any debt above 8%, (3) fully fund emergency reserve, (4) then split between retirement investing and lower-rate debt prepayment.
How do I tell my lender to apply extra payments to principal?
Most online portals have a 'Pay Extra Principal' or 'Principal-Only Payment' option separate from the regular payment field. If you're mailing a check, write 'For principal reduction only' on the memo line and include a brief letter saying: 'Please apply this $X payment entirely to principal and do not change the next scheduled payment date.' Then verify on your next statement that the principal balance dropped by your extra amount.
Does this calculator handle variable-rate loans?
No — it assumes a single fixed rate for the remaining term, like a fixed mortgage, auto loan, or personal loan. For an ARM after reset, an income-driven student loan, or a credit card with variable APR, the savings figures are only accurate until the rate changes. Re-run the calculator with the new rate and remaining balance whenever your rate adjusts.
What about taxes — does prepaying reduce my mortgage interest deduction?
Yes. If you itemize and deduct mortgage interest under IRS Publication 936, prepaying reduces the interest you pay and therefore your deduction. But the deduction only refunds a fraction of the interest (your marginal tax rate, typically 22-32% federal), so prepaying still saves more than the lost deduction. With the higher post-2017 standard deduction, many homeowners don't itemize anyway — confirm with your tax situation.
If I make one extra payment, will my monthly payment go down?
Not automatically. Most fixed-rate loans keep the scheduled payment unchanged and simply finish earlier. To lower the monthly payment instead of shortening the term, you typically need a 'recast' (mortgage) or 'reamortization,' which the servicer performs after a substantial principal prepayment — often for a small fee. Recasting is rare for auto and personal loans; the standard outcome is a shorter payoff date with the same monthly bill.
Why does the payoff date differ from my servicer's projection?
Three common reasons: (1) your servicer's projection assumes today's payment continues unchanged with no extras, while this calculator models your proposed extra; (2) timing of when extra payments post (mid-cycle vs end-of-cycle) shifts the result by a few months over a 30-year horizon; (3) your servicer may include scheduled escrow disbursements in its balance figure. For an authoritative payoff date, request a current amortization schedule from the servicer after a sample month of accelerated payments.
Does paying extra hurt my credit score?
No. Paying ahead reduces your reported balance and lowers your credit utilization on revolving accounts (a positive signal). For installment loans, prepayment doesn't hurt your score and paying the account off may temporarily shave a few points (you lose an active tradeline) but the long-term effect on financial health is overwhelmingly positive.
