Negative equity arises when a loan balance exceeds the vehicle's market value. It is common early in long loan terms, because vehicles depreciate fastest in the first years while the balance falls slowly.
It matters at the point of sale or trade. A seller with negative equity has to find the difference in cash to clear the lien, and not all of them can.
Rolling the shortfall into a new loan carries it forward and deepens the problem on the next vehicle.
Why it matters
If a private seller is underwater, the lien may not get discharged when you pay them, which leaves the lender's claim attached to your vehicle.
How to check it
Ask for a written payoff figure from the lender and pay the lender directly rather than the seller where possible.
Does this apply to the car you are looking at?
Run the VIN or plate and see what is actually on record.
Related terms
Definitions are general guidance, not legal advice. Title rules, total loss thresholds and inspection requirements are set by each state and change over time, so confirm the position with the motor vehicle agency for the state the vehicle is titled in before relying on it.