I completed a previous Master’s degree in F-1 status in the U.S., but did not apply for and have approved OPT based on that degree. Would I be eligible for OPT during/after completion of a second Master’s degree in the U.S.?

Students in F-1 status, enrolled as a full-time student for at least one full academic year (Fall + Spring term) in their degree program, are eligible for up to 12 months of Optional Practical Training (OPT) authorization per degree level at a progressively highly degree level in a student’s lifetime.

If you have not been authorized for OPT at the Master’s degree level previously, or at a higher degree level previously, then you would be eligible for 12 months of OPT during/after completion of your second Master’s degree program at MIT. 

If you applied for OPT at the Master’s degree or higher level previously, and that application was approved by USCIS, whether you actually worked on that OPT authorization, it would count as OPT used at that degree level and you would not be eligible to apply for or be approved for OPT at the same degree level or at lower degree level. 
It does not matter if the new degree is in a different field of study, or if there has been many years between the degrees. The 12 months per degree level is a lifetime limit.

If you were approved for OPT at the Master’s degree level, and then went on to a higher degree in the U.S. (such as a Ph.D./doctoral degree), a student would be eligible for OPT at that higher degree level. 

For more information on F-1 Employment, please see the ISO Employment Information webpages.