California Auto Insurance: Do You Need Separate UM and UIM Policies?

Quick Answer

In California, you are not required to purchase Uninsured Motorist (UM) and Underinsured Motorist (UIM) coverage as separate policies. Both coverages are optional add‑ons to your standard auto liability policy, and insurers typically offer them together in a single UM/UIM endorsement. However, you can choose to buy only one, or decline both, if you prefer.

Understanding UM and UIM Coverage

Both UM and UIM protect you when another driver is at fault but lacks sufficient insurance to cover your losses.

Uninsured Motorist (UM) Coverage

UM pays for bodily injury and, in some policies, property damage when the at‑fault driver has no insurance at all.

Underinsured Motorist (UIM) Coverage

UIM steps in when the at‑fault driver's liability limits are lower than your own medical expenses or lost wages. It covers the gap up to the limit you select.

California Legal Requirements

California law does not mandate UM or UIM coverage. The state's minimum auto insurance requirements are:

• $15,000 for injury/death to one person
• $30,000 for injury/death to two or more persons
• $5,000 for property damage

These are liability limits only; they do not include UM or UIM. Drivers may decline UM/UIM by signing a written waiver on the insurance application.

Why Insurers Bundle UM and UIM

Most California insurers package UM and UIM together because the risks they cover are closely related. Bundling offers several benefits:

• Simplified paperwork – one endorsement instead of two separate contracts.
• Potential cost savings – insurers often discount the combined limit.
• Clearer coverage limits – you set a single dollar amount that applies to both UM and UIM claims.

When You Might Choose Separate Coverage

Separate UM and UIM policies are rare, but a few scenarios could justify it:

• You have a very high medical expense risk (e.g., chronic condition) and want a large UIM limit but a modest UM limit.
• You are negotiating a group or employer‑sponsored plan that only includes one of the coverages.

In such cases, you would need to discuss custom endorsements with your insurer, and premiums may be higher.

Cost Considerations

Adding UM/UIM typically increases your premium by 5–15% of the base liability cost, depending on the limit you select and your driving record. Below is a sample cost range based on 2024 data from the California Department of Insurance.

How to Add or Decline UM/UIM on Your Policy

When you apply for or renew an auto policy, you will see a section titled "Uninsured/Underinsured Motorist Coverage." To add the coverage, simply select the desired limit and sign the endorsement. To decline, you must sign a written waiver stating you understand the risks of not having the protection.

Impact on Claims and Settlements

If you are injured by an uninsured driver and have UM coverage, your insurer will pay your medical bills up to your UM limit, regardless of the at‑fault driver's financial situation. If the driver is underinsured, UIM will cover the shortfall between the at‑fault driver's liability limit and your medical costs, again up to your selected limit.

Both coverages are subject to the same deductible rules as your liability policy, and they may be coordinated with your health insurance to avoid duplicate payments.

Key Takeaways

• UM and UIM are optional in California; they are not required by law.
• Most insurers offer them together in a single endorsement, not as separate policies.
• You can decline both, but doing so leaves you vulnerable to uninsured or underinsured drivers.
• Bundled coverage usually saves money and simplifies claims.
• Consider your personal risk profile and health coverage when selecting limits.