Tex. Ins. Code § 1201.213
An individual accident and health insurance policy must contain the following provision:
"Proof of Loss: For a claim for loss for which this policy provides any periodic payment contingent on continuing loss, a written proof of loss must be provided to the insurer at the insurer's designated office before the 91st day after the termination of the period for which the insurer is liable. For a claim for any other loss, a written proof of loss must be provided to the insurer at the insurer's designated office before the 91st day after the date of the loss. Failure to provide the proof within the required time does not invalidate or reduce any claim if it was not reasonably possible to give proof within the required time. In that case, the proof must be provided as soon as reasonably possible but not later than one year after the time proof is otherwise required, except in the event of a legal incapacity."
Tex. Ins. Code § 1201.213