Should You Pay Off a Car Loan Early? The Rule, and the Three Exceptions

The decision rule, stated once

Money used to clear a loan earns exactly the loan's interest rate, guaranteed and tax-free, because every euro of principal removed is a euro that stops accruing interest. So the comparison is not between paying off and not paying off. It is between the loan rate and the after-tax rate on whatever else the money would have done. Above the loan rate, keep the cash; below it, clear the loan. In the worked example the break-even is not approximately 7 percent, it is 7 percent: run the alternative at exactly the loan rate and the two paths land on month 60 with the same balance to the cent.

That rule has an order of operations in front of it. First an emergency fund, because cash sunk into a car loan cannot be withdrawn when the boiler fails and will come back as card debt at 20 percent. Then the highest-rate debt: clearing a 7 percent car loan while a card runs at 20 percent is strictly worse than clearing the card, by thirteen points a year on every euro moved. Only when both are settled does the loan-rate-versus-savings-rate comparison decide anything.

Where the $1,431 goes when you look closely

The headline saving is the difference between the remaining scheduled payments, $14,257, and the payoff quote, $12,826. That gap is real interest you will not pay. It is also the number every refinance advert quotes, and it overstates the benefit, because it silently assumes the $12,826 was doing nothing. Put that sum in a 4 percent account instead and draw the 36 remaining payments out of it, and it does not quite last: month 60 arrives $663 short. That $663, not $1,431, is what the early payoff was worth against that particular alternative.

The same arithmetic explains why paying off late in the term is almost pointless. An amortising loan front-loads its interest: on this loan, $2,330 of the $3,761 total is charged in the first 24 months. Settle at month 48 instead and the saving falls to $175, because by then almost every payment is principal. If a lender is pressing you to refinance at year four to escape interest, there is barely any interest left to escape.

Precomputed interest and penalties: read the contract first

Everything above assumes a simple-interest loan, where interest is charged each month on the balance that actually remains. A precomputed loan works the other way: the whole finance charge is fixed at signature and added to the debt, and paying early earns you a rebate of unearned interest rather than a smaller balance. Where that rebate follows the Rule of 78s, it is weighted so more of the charge counts as earned in the early months. On the same loan, the month-24 quote becomes $12,888 rather than $12,826 and the saving drops from $1,431 to $1,369 — $62 taken off the top for nothing.

That $62 sounds trivial because the rate is modest. Run the same rebate on a subprime deal — $20,000 at 15 percent over 72 months, settled at month 24 — and the Rule of 78s costs $428 instead of $62, because the finance charge it is redistributing is $10,449 rather than $3,761. Add a prepayment penalty, commonly a percentage of the outstanding balance, and the erosion compounds. Before transferring anything, ask the lender for a written payoff quote with a validity date and check it against the balance your own amortisation gives; if the quote is higher, the difference is what the contract is charging you for leaving early.

Frequently asked questions

Does paying a car loan off early hurt my credit score?

It can nudge a score down slightly and temporarily, because closing an instalment account removes an actively-paid loan from the mix and shortens the average age of open accounts. The effect is small and it reverses. Scoring models are national and differ in how they weight this, so treat it as a footnote rather than a reason: a few points on a score is not worth $1,431 of interest, nor is it worth paying off a loan you cannot comfortably afford to clear.

Is it better to pay a lump sum or add extra to each monthly payment?

Whatever reaches the principal soonest wins, so a lump sum today beats the same amount spread over a year — but only if the lender applies it to principal rather than treating it as an advance payment of future instalments. Say so in writing when you send it. Extra monthly amounts are easier to sustain and still work: on the $20,000 loan at 7 percent, they shorten the schedule the moment they land, because the following month's interest is charged on a smaller balance.

How do I tell whether my loan is simple-interest or precomputed?

Look at how the contract states the debt. A simple-interest loan shows a principal and a rate, and your statement carries a balance that falls each month. A precomputed loan states a total amount payable fixed at signature, often with a clause describing how unearned interest is rebated on early settlement — the phrase Rule of 78s, or a reference to the sum-of-the-digits method, is the giveaway. If the clause is there, ask for the payoff quote in writing before you decide, because the saving will be smaller than the interest column suggests.