Is it unethical to change my plan for PhD for another PhD program after committing by the deadline?

Question

Last year I got into a physics PhD program at university A in the US, and now I'm doing a one-year master's program at university B (which has a much higher ranking) by deferring a year at A. A is asking me to let them know about my final decision by the end of this month so that in case I don't want to come back this year, they still have a chance to recruit another student.

My situation is I actually have submitted applications to my current university B for their PhD program (which has a different focus on physics, and there is no professor at A studies this direction), and the admission result will be available in another 6-8 weeks. I'm honestly not 100% sure which field I really want to pursue at this moment. My question is if I'm telling A I'm coming back, but later at some point I changed my mind, is it unethical if I tell them I want to change my plan and commit to B as their research focus better suits my interest?

Answer 1

It is unethical, in my opinion.

My question is if I'm telling A I'm coming back, but later at some point I changed my mind, is it unethical if I tell them I want to change my plan and commit to B as their research focus better suits my interest?

You already know that there is a chance that you will accept the offer from B (if you get the offer), and they don't, probably you also like the program at B more, yet you still want to tell them that you will commit to the program A.

You are wasting their time, and it is unethical. You should let them know about your plans, so "they still have a chance to recruit another student", or they can still give you some time to wait for the result.

Also, you had a chance to decline months ago without any ethical issue. Can I decline a PhD offer after deferral, and how to communicate with my professors for reapplying other PhD programs?