F-1 students are eligible for up to 12 months of initial full-time OPT for each higher degree level - a year for a Bachelor's, Master's and Doctorate
This does NOT apply if going to a lower degree (i.e. Master's to Bachelor's) or to a similar degree (i.e. Master's to second Master's degree).
Post-Completion OPT years cannot be combined or split.

You will not receive additional OPT time if you complete another degree at the same level (e.g., two master's degrees) or a lower level (e.g., complete a master's degree and then go back to school to complete a second bachelor's degree).