Negative Equity Rollover Calculator
Owe more than your car is worth? See how rolling that negative equity into a new loan inflates the balance, payment and interest, how long you stay underwater, and what paying the gap in cash or a shorter term would save.
How it works
Negative equity = old balance − trade value · Financed = new price + sales tax + fees − rebate − down + negative equity · Payment = amortize(financed, APR, term) · Loan-to-value = financed ÷ new price · Underwater until the balance falls below the car’s depreciated value
Rolling negative equity forward adds the gap between your old loan balance and the car’s trade value on top of the new purchase, so you finance more than the new car is worth from day one. That pushes your loan-to-value above 100%, meaning you are underwater again immediately and stay there longer — a cycle that deepens with each trade. The calculator adds sales tax (with the trade-in credit most US states give), fees and any rebate, then shows the extra monthly payment and the total extra interest the buried old debt costs. The options table compares rolling the debt in with paying the gap in cash and with a shorter or longer term. Using the depreciation rates under More options, it also tracks the new car’s value against the loan balance to estimate how long you will be underwater, with and without the rollover. If the loan-to-value is above what lenders usually accept, it tells you how much cash would bring it down.
Worked example
You owe $18,000 but the old car is worth $14,000 — $4,000 of negative equity. On a $28,000 new car with $2,000 down and 6% sales tax on the price minus the trade ($840), you finance $28,000 + $840 − $2,000 + $4,000 = $30,840. At 7% over 72 months that is about $525.79 a month, roughly $68 more than the $457.60 you would pay if you covered the $4,000 in cash, and about $910 of extra interest over the loan. The loan starts at 110% of the car’s price, and with typical depreciation you would owe more than the car is worth for about 3 years 4 months, against about 2 years without the rollover.
Sources: CFPB — Should I trade in my car if it’s not paid off? · FTC — Financing or leasing a car
Frequently asked questions
Is rolling over negative equity a bad idea?
It is usually costly: you pay interest on debt for a car you no longer own and start the new loan underwater, which makes the next trade harder too. Paying the shortfall in cash, or waiting until you have positive equity, avoids the trap. The options table shows the difference in payment, interest and time underwater.
What is negative equity?
It is owing more on your loan than the car is worth — also called being “upside down” or “underwater.” It is common early in a long loan because cars depreciate faster than the balance falls.
How long will I be underwater?
Until the loan balance drops below what the car is worth. The calculator estimates it month by month from your loan and the depreciation rates under More options (about 20% in the first year and 15% a year after that by default). Rolling in old debt, a small down payment and a long term all push that date further out.
Will a lender approve a loan with negative equity?
Often yes, up to a limit: many lenders cap auto loans at about 120%–150% of the car’s value. If your loan-to-value is above the cap you set, the calculator shows how much more cash would bring it down.
How do I avoid it next time?
Put more down, choose a shorter loan term, and pick models that hold value. Keeping the loan term at or below the time you plan to own the car keeps your balance below the car’s value. Gap insurance protects you while you are underwater, but it does not reduce the debt.
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Educational estimate, not financial advice — real quotes, taxes and fees vary by lender, state and vehicle.