What must an insurer include when demanding subrogation from a third party?

The correct answer highlights that when an insurer demands subrogation from a third party, it is essential to include the deductible amount. This is crucial because the deductible represents the portion of the claim that the insured is responsible for covering. In the process of subrogation, the insurer seeks to recover the total amount paid out on a claim from a third party who may have been responsible for the loss. Including the deductible ensures that the third party is aware of the complete financial impact of the claim — including what the insured had to bear.

The other options do not carry the same necessity in this context. While the insured's consent to subrogate may be relevant in some situations or jurisdictions, it is not a required component of the subrogation demand itself. The total cost of damages, while informative, may not encapsulate the follow-through of the financial arrangements regarding the deductible. Lastly, while having a damage assessment report can substantiate claims and details of damages, it is not specifically mandated to be included in the initial demand for subrogation. Therefore, the deductible amount is the critical addition that aligns directly with the insurer's recovery efforts.