# Underinsured motorist coverage (UIM)

> Underinsured motorist coverage (UIM) defined: how it pays when the at-fault driver's liability limits are too low to cover your injuries or losses.

Canonical page: https://statecover-guide.com/glossary/underinsured-motorist-coverage/  
Last reviewed: October 28, 2026 by the StateCover Guide editorial team  
General information, not legal or insurance advice.

## Quick answer

Underinsured motorist (UIM) coverage protects you when the driver who caused the crash has liability insurance, but not enough to pay for your injuries or other losses. Your own policy then covers the gap, up to your UIM limit.

## How it works

The NAIC describes UIM as a policy option for losses caused by a motorist whose coverage is not enough, compensating the injured person for the difference between their losses and the at-fault driver's liability coverage.

Example: another driver with $25,000 of bodily injury coverage causes $70,000 of injuries to you. Their insurer pays $25,000. If you carry $100,000 of UIM coverage, your insurer can pay the remaining $45,000. States calculate UIM payments in different ways, so the amount can vary.

Key points:

- **Often sold with UM.** Underinsured coverage is commonly paired with uninsured motorist coverage. Texas, for example, describes them together as uninsured/underinsured motorist coverage.
- **Offered, and declined in writing.** In Texas, insurers must offer UM/UIM coverage, and you must tell the company in writing if you don't want it.
- **What it can pay.** In Texas, UM/UIM pays medical and car repair bills when the other driver didn't have enough insurance, and you pay a deductible on these claims.
- **Your limits.** UIM pays only up to the limit you chose, so low UIM limits may not close a large gap.

## Related terms

- [Uninsured motorist coverage](https://statecover-guide.com/glossary/uninsured-motorist-coverage/)
- [Stacking](https://statecover-guide.com/glossary/stacking/)
- [Liability limits](https://statecover-guide.com/glossary/liability-limits/)
- [Bodily injury liability](https://statecover-guide.com/glossary/bodily-injury-liability/)
- Guide: [Uninsured motorist coverage: UM, UIM and how much to buy](https://statecover-guide.com/coverage/uninsured-motorist/)

## Sources

- [NAIC, Glossary of insurance terms](https://content.naic.org/glossary-insurance-terms) — definition of underinsured motorist coverage
- [Texas Department of Insurance, Auto insurance guide](https://www.tdi.texas.gov/pubs/consumer/cb020.html) — UM/UIM coverage, the duty to offer it, written rejection and deductibles