Short answer: Use 60 days. Federal law requires group health plans and their insurers to allow at least 60 days after Medicaid or CHIP ends for loss of eligibility; the older 30-day window in Texas Insurance Code 1207.002 does not shorten that.
Texas Insurance Code 1207.002(b) lets a person who loses Medicaid or CHIP eligibility enroll in a group plan if the written request comes within 30 days. That predates the 2009 federal CHIPRA change, which requires an employer group health plan and its insurer to permit enrollment if the request is made not later than 60 days after the Medicaid or CHIP coverage terminates.
So for an employer’s group health plan, treat 60 days from the termination date as the deadline. Have the employee get the HHSC notice showing the end date, and submit the request well before day 60.
The federal right is tied to coverage ending because of loss of eligibility. If the family instead asked to cancel Medicaid or CHIP, check the plan administrator’s position before relying on the special enrollment right.