Final answer:
Yes, you can apply for OPT for a master's degree even if you have a Ph.D. but haven't used OPT at that level. OPT is available at each educational level, and having a higher degree does not affect your eligibility.
Step-by-step explanation:
The question "Could I apply for OPT for the master's degree if I have gotten a Ph.D. before but haven't used the OPT?" addresses the eligibility for Optional Practical Training (OPT) in the context of U.S. immigration and student visas.
If you have earned a Ph.D. and are currently pursuing a master's degree, you may still be eligible to apply for OPT based on the master's degree program. OPT is a temporary employment authorization for F-1 students to gain practical experience directly related to their major area of study. According to the regulations, you can use OPT at each education level (bachelor's, master's, and doctoral). Since you have not previously used OPT at the doctoral level, it does not preclude you from applying for OPT at the master’s level. The key criteria include being enrolled in an accredited institution and having been a full-time student for at least one full academic year. Furthermore, the proposed employment must be directly related to your major field of study. Therefore, the answer to the question is a) Yes, you can apply for OPT for the master's degree program even if you have previously obtained a Ph.D. but have not utilized the OPT for that educational level. Just make sure to comply with all the necessary requirements and timelines set out by U.S. Citizenship and Immigration Services (USCIS).