When can the Subrogation be requested from the Insurer?

Subrogation by definition means the Insurer taking your rights on the property insured post settlement of claim by them. Once the claim has been settled by the insurer, they get a declaration vide which the insured pass on their right on the property to the insurer. e.g. Under marine insurance, thru subrogation insurer can recover the loss from the transporter. Under Fire Insurance, the insurer post settlement of the claim take right of salvaging the property and whatever amount is recovered belongs to the insurer.

One can request his/her insurer to subrogate a case only if he/she have comprehensive motor insurance and not a 'third party only' policy.