UM/UIM Stacking Calculator.

How this calculator works

UM/UIM stacking adds together the uninsured-motorist limits from multiple policies covering members of the same household — and, in many states, employer-fleet UM coverage and umbrella with UM follow-form. The total stacked coverage is often substantially higher than the client's own primary UM limit alone. State law determines whether stacking is permitted and under what conditions.

State categories used in this calculator

• Opt-out (Florida). Stacking applies by default. The insured had to affirmatively reject stacking on a state-approved form. If the rejection form is missing or invalid, stacking applies even on a policy issued as non-stacking. Read more on Florida UM rules →
• Default-allowed. Pennsylvania, Illinois, Georgia (limited), West Virginia, and others allow stacking unless an anti-stacking clause meets specific statutory language. Pennsylvania has the most generous regime.
• Prohibited / restricted. New York, California, Virginia, and others prohibit or sharply restrict stacking by statute. A single UM limit per policy regardless of household policy count.
• Conditional. Many states allow stacking under specific conditions (multi-vehicle policies, intra-policy only, etc.). When unsure, consult state-specific case law or commission a coverage analysis on the client's actual policies.

What this calculator does NOT do

This is an estimate based on user inputs. It does not verify whether the listed policies actually exist, whether stacking rejection forms are on file, or whether umbrella follow-form language is present. To convert estimates into a defensible coverage map for tender, commission an actual coverage verification on the client's policy file. The deliverable includes attestation from a licensed investigator.