Which document must be signed for an insurance contract amendment to be considered valid?

An insurance contract amendment is considered valid when it is documented appropriately, reflecting the agreement of all parties involved, especially the insurer. A written signed waiver by the insurer is crucial because it formally acknowledges the changes in the terms of the contract. This signed document provides clear evidence of the insurer's acceptance of the amendment, ensuring both the insurer and the insured are on the same page regarding any modifications.

Without this signed waiver, there could be ambiguity about whether the insurer has agreed to the changes, potentially leading to disputes later. The other options lack the necessary requirements for formalizing changes to the insurance agreement, as oral agreements or documents signed only by the insured do not fulfill the legal criteria for amending contracts in this context. Periodic reviews, while beneficial for assessing coverage needs, do not constitute amendments themselves unless accompanied by a formal signed document from the insurer.