noun
endorsement
In plain English
A document attached to your policy that adds, removes, or modifies coverage.
Every policy has them. Some are standard (the BOP form, the auto form). Some are negotiated (an additional insured endorsement, a higher sublimit). The endorsements are where most of the actual coverage decisions live.
What it covers
Whatever the endorsement says. Could add a coverage, exclude a peril, change a limit, name an additional insured, or modify dozens of policy provisions.
What it does not cover
Endorsements are NOT 'add-ons' in the marketing sense. Many of them remove coverage. Always check what was added vs. what was taken away.
Where it trips people up
Insurers can attach endorsements at renewal that quietly narrow coverage. The premium might not change. We compare the prior year's form list to the new one as part of every renewal review.
The technical version
A written document attached to and forming part of an insurance policy that modifies the original terms; may broaden, restrict, or otherwise alter the coverage. Also called a rider.