Answer:
It is not altogether clear what you mean. However, since this appears in the section of "Auto Accidents and Insurance Claims", you may have received a demand letter of some type from someone who is making a claim against you.
First and foremost, if you had liability insurance, or you even think that you had liability insurance that may cover the incident, deliver the demand letter to the insurer to handle (keep a copy for yourself). In that way, you will initially have complied with the insurer's requirement that you timely place it on notice of the claim so that it may defend you. You willl have to later cooperate with the insurer in its defense of you, but giving timely notice of the claim is the initial step.
If you are using use the term "rebuttal" in a more formal sense, it essentially means a reply to an answer. That is, if you make an assertion, and the other part answers it (essentially, defends against it), a rebuttal is your reply. Technically, it is limited in scope to addressing new matter that the other party raises in its answer, rather than a restatement of your original claim. If used in this way, there is really no reason that you give the person notice that you are sending one; just draft a factual, ideally, non-emotional statement.
This is about the best that can be done with your question as phrased. If you wish to clarify it, feel free to do so.