What document is issued by an insurer that states a change in the terms and conditions of a policy?

The document that is issued by an insurer to state a change in the terms and conditions of a policy is known as an endorsement. An endorsement modifies the original policy provisions and can either add coverage, exclude certain risks, or make adjustments in the terms. This allows both the insurer and the insured to clarify and amend the coverage as needed without having to rewrite the entire policy.

In contrast, a declaration typically contains the basic details of the policy such as the policyholder's name, the coverage amounts, and the effective dates, but it does not modify the terms. The policy schedule provides a summary of the coverage and limits applicable to the insured, but again, it is not responsible for changing the policy conditions. The policyholder agreement, while it may outline the rights and responsibilities of both parties, does not serve the purpose of formally altering the insurance policy terms. This is why the endorsement is the correct answer for indicating changes to an existing policy.