What a demand letter does, and when to send it
A demand letter opens the settlement negotiation on paper. Before it, the adjuster has a claim number, a police report and whatever bills have trickled in; after it, your account of liability, a complete schedule of losses, the documents behind it, and a figure to weigh against the policy limits. Adjusters write their valuation memo from that package, so the letter is a brief rather than a plea, judged on whether every claim in it is backed by a page in the enclosures.
Timing decides more than wording. The demand goes out once you reach maximum medical improvement: a treating physician says you have recovered as far as you will, or has written down what is permanent and what future care will cost. A demand sent mid-treatment prices an injury nobody has finished measuring, and the release that ends the claim will not reopen for the surgery recommended a month later. The exception is a filing deadline that is close; then the demand is written from the prognosis you have, with a licensed attorney watching the calendar.
Address the letter to the adjuster on the at-fault party’s liability policy, claim number in the subject line; a claim on your own coverage, an uninsured motorist claim for instance, gets the same letter, sent to your own carrier. Use a method that produces a delivery record and keep the package exactly as mailed.