(a) Except as provided by Subsection (b) or (d), an insurer shall notify a claimant in writing of the acceptance or rejection of a claim not later than the 15th business day after the date the insurer receives all items, statements, and forms required by the insurer to secure final proof of loss.
(b) If an insurer has a reasonable basis to believe that a loss resulted from arson, the insurer shall notify the claimant in writing of the acceptance or rejection of the claim not later than the 30th day after the date the insurer receives all items, statements, and forms required by the insurer.

(c) If the insurer rejects the claim, the notice required by Subsection (a) or (b) must state the reasons for the rejection.
(d) If the insurer is unable to accept or reject the claim within the period specified by Subsection (a) or (b), the insurer, within that same period, shall notify the claimant of the reasons that the insurer needs additional time. The insurer shall accept or reject the claim not later than the 45th day after the date the insurer notifies a claimant under this subsection.