UM/UIM coverage in Georgia: how it actually works (and why most drivers carry less than they think)

Most Georgia drivers think their auto policy will protect them if they get hit by an uninsured or underinsured driver. Most are wrong about how it works. The difference between 'added-on' and 'reduced-by' UM coverage — a single radio button on the policy declarations page — is the difference between recovering full damages on a serious case and being capped at the at-fault driver's policy minimums. Few people read their declarations page closely enough to notice. Most agents do not explain it. The choice is locked in by Georgia statute the moment you sign.

What follows is what UM/UIM coverage actually does in Georgia, the two stacking models, and how to tell which one your policy uses before you need to use it.

Why UM/UIM coverage exists at all

Uninsured/underinsured motorist coverage is the part of your own auto policy that pays YOU when the at-fault driver does not have enough insurance — or any insurance at all — to cover your damages. It is your own carrier writing you a check, against the deficiency in the at-fault party's coverage.

Georgia requires every auto liability policy to offer UM/UIM coverage. Drivers can reject it in writing, but the default is to include it. The minimum offered limit is $25,000 per person / $50,000 per accident, matching Georgia's mandatory liability minimums under O.C.G.A. § 33-7-11.

Why this matters: Georgia's minimum liability limits are among the lowest in the country. Roughly one in eight Georgia drivers is uninsured at any given moment. And of those who are insured, a large share carry the legal minimum — $25,000 per person — which is exhausted in a single trip to the emergency room for a moderate injury. UM/UIM is the safety net for the gap between what the at-fault driver carries and what your case is actually worth.

The two stacking models — and why they are NOT the same

Georgia is one of the few states that lets policyholders choose between two materially different UM/UIM stacking models. The choice is made at the time the policy is issued and locked in by O.C.G.A. § 33-7-11 unless affirmatively changed. Drivers rarely realize they have made a choice at all.

Added-on (also called "true excess" or "stacking") coverage

Added-on UM coverage stacks ON TOP of the at-fault driver's liability coverage. If the at-fault driver carries $25,000 and your added-on UM is $100,000, you have access to $25,000 from them PLUS $100,000 from your own UM — a total of $125,000.

This is the model most drivers assume they have. It maximizes recovery in a serious-injury case. It is also typically a few dollars more per month in premium than the alternative.

Reduced-by (also called "non-stacking" or "offset") coverage

Reduced-by UM coverage is reduced dollar-for-dollar by whatever the at-fault driver's liability policy paid. If the at-fault driver carries $25,000 and your reduced-by UM is $100,000, your UM is reduced by the $25,000 they paid — leaving $75,000 from your own policy. Total available: $100,000, not $125,000.

Reduced-by is the cheaper option. It is also the default that some carriers offer first if the agent does not specifically ask. A driver who thinks they have $100,000 in UM coverage may actually have $75,000 in usable coverage on the cases that matter most.

A working example to make this concrete

A Marietta driver is rear-ended by a pickup driver running a red light. Plaintiff has $200,000 in actual damages — emergency room, surgery, three months of physical therapy, lost wages from a software job, future medical care for a herniated disc. The at-fault driver carries Georgia minimum liability of $25,000 per person. Plaintiff carries $100,000 in UM/UIM.

Same plaintiff. Same accident. Same nominal coverage limits. Recovery delta of $25,000 — and on cases with bigger damages and bigger UM limits, the delta grows linearly. On a $1,000,000 case with $250,000 UM, the difference is $250,000 in the plaintiff's pocket.

How to tell which one your policy uses

The declarations page (the cover sheet of your auto policy) usually shows the UM coverage limit but rarely labels the stacking model in plain English. Look for any of these phrases:

If the declarations page is ambiguous, the actual policy form (the 30+ page document) will spell it out. The sections to look for: 'Limit of Liability — Uninsured Motorist' or 'Other Insurance — Uninsured Motorist Coverage'. Reduced-by language uses phrases like 'limit shall be reduced by amounts paid' or 'in excess of and not in addition to' the at-fault coverage.

Stacking across multiple policies

Georgia law historically allowed UM coverage to stack across multiple policies in the same household — a driver injured in one vehicle could potentially access UM coverage from other vehicles in the same household policy. The 2008 amendments to O.C.G.A. § 33-7-11 narrowed this significantly. Whether a multi-policy stack is available now depends on the specific policy language and the relationship between the policies.

Practical implication: in a household with multiple vehicles on multiple policies, an injured family member may have access to UM coverage from policies they did not personally pay for. The analysis is fact-specific. We always check at the start of a serious case.

What about umbrella policies?

A personal umbrella policy provides additional liability coverage above the underlying auto and homeowners policies — typically $1 million or more. Most umbrella policies do NOT automatically provide UM/UIM coverage. The policyholder has to specifically request and pay for UM/UIM on the umbrella, and most do not. So a household with a $1 million umbrella may have $1 million in liability protection (paying out to others) but only $100,000 in UM (recovering from underinsured at-fault drivers).

If you have an umbrella policy, ask your agent specifically: does it include UM/UIM? If not, what does it cost to add? On serious-injury exposure for high earners, the cost-benefit usually favors adding it. The math is straightforward and we walk clients through it during the consultation.

What we look for at the start of every case

On every serious personal injury case, the first investigation step is identifying every layer of available coverage. UM/UIM is often where the real money sits.

Each layer requires its own demand and its own settlement. Failing to identify a layer at the start can mean leaving money on the table that the plaintiff cannot recover later.

What you can do today (even if you are not currently injured)

These are not things to do AFTER an accident. The coverage in place at the moment of impact is the coverage that applies. Increasing limits or switching from reduced-by to added-on does not retroactively help.

The honest read

UM/UIM coverage is one of the highest-value parts of an auto insurance policy and one of the least understood. Most drivers carry less than they think, and the difference between 'added-on' and 'reduced-by' usually is not explained when the policy is sold. The cases where this difference matters most are exactly the cases where the plaintiff cannot afford the gap — serious injuries, real damages, an at-fault driver who carries the legal minimum.

If you have been injured and are working through the coverage analysis, the consultation is free. We will pull every policy in the case, identify every layer, and tell you what is available before any settlement is signed. That is part of the work — not an extra.