Tex. Insurance Code § 846.257

(a) The initial enrollment period for employees meeting the participation criteria must be at least 31 days, with a 31-day annual open enrollment period. The enrollment period must consist of an entire calendar month, beginning on the first day of the month and ending on the last day of the month. If the month is February, the period must last through March 2.

(b) A multiple employer welfare arrangement may establish a waiting period.

(c) A new employee who meets the participation criteria may not be denied coverage if the application for coverage is received by the multiple employer welfare arrangement not later than the 31st day after the later of:

(1) the date on which the employment begins; or

(2) the date on which the waiting period established under Subsection (b) expires.

(d) If dependent coverage is offered to participating employees under the terms of a multiple employer welfare arrangement's plan document:

(1) the initial enrollment period for the dependents must be at least 31 days, with a 31-day annual open enrollment period; and

(2) a dependent of a new employee meeting the participation criteria established by the arrangement may not be denied coverage if the application for coverage is received by the arrangement not later than the 31st day after the later of:

(A) the date on which the employment begins;

(B) the date on which the waiting period established under Subsection (b) expires; or

(C) the date on which the dependent becomes eligible for enrollment.

(e) A late-participating employee or dependent may be excluded from coverage until the next annual open enrollment period and may be subject to a one-year preexisting condition provision as described by Section 846.202. The period during which a preexisting condition provision applies may not exceed 18 months after the date of the initial application.