Should I ask for deferral before accepting a PhD offer or after accepting it? I am currently in a PhD program, and have applied and received offers to start another (changing fields). Both are in the US, so I do not need to finish a master's or anything. The plan was that I will finish this year in my current PhD program, take some useful courses, get my master's degree, and peacefully leave in good academic standing and start the new program. For some personal reasons, which lead to serious bureaucratic issues, I had to take a leave of absence from my current program. So now, I would have to just leave my current program with very few courses taken and start my new PhD in Fall. 

I know all of the departments I have offer from are ok with that, but I am NOT! I think it may look really bad on my CV to have just a few courses from my current PhD program, and abandon it in the middle of a leave of absence and start in a different field. Plus, although I am changing fields, some knowledge from my current field, the courses I was going to take, and the master's degree, are going to be extremely useful at many levels (super useful transferrable skills and a master's degree in a field and from a very prestigious school that can significantly improve my qualifications and open more doors for industry jobs after my PhD). Additionally, just for the sake of my confidence, feelings, and my relationship with my current classmates and professors, I think it would make a big difference if I go back after my leave ends, finish this year, and leave with good grades at a nice point (end of the master's courses), especially because the department was very kind to me and helped me a lot with the personal and bureaucratic issues.

I have to respond to my offers by April 15th, and I wonder if I should talk to the departments I am considering, and ask them if I can put their offer on a hold and join the new program in 2021 after finishing my master's. I know that most departments are going to be struggling financially because of the pandemic, and that makes me afraid that they may really dislike the idea and reject that request immediately. So, I think it may be better if I accept their offer, then ask them to defer the start date for a year. That being said, there are two risks with that: 1. If they decide not to take new PhD's at all in 2021 because of the pandemic, I will have trouble with starting then, especially because all are small departments with &lt;10 PhD students a year. 2. One might be ok with that and another might not, so if I ask now, I can choose the one that allows me to do that. On the other hand, if I ask now and they reject, there is no way I can do that after accepting the offer, and going for a likely suggestion that I reapply next year is very risky. So, I think I have a higher chance for getting a positive answer to my request from each individual department if I present them with a fait accompli, i.e. accept their offer, then say I want to defer, but possibly a lower chance than getting one positive response if I ask all of them now (but that might not be from my current top choice). I know for a fact that some departments always reject the request to defer an offer, but sometimes accept to defer the start date when a new student asks for it after accepting their offer.

So, here are my questions:


Should I ask the new departments I have offer from if they allow me to go back and finish my current program and defer my enrollment in their program until next year, or should I accpet the offer, and then ask them?
Does it make sense to choose based on whether they allow me to do that or not? (and so, ask now)
Congratulations on your offers.  This is really four questions.


Would I benefit from a deferment?


It sounds like you feel bad about "abandoning" your current program.  You should not.  You probably owe them nothing.  PhD programs benefit universities more than students.  Completing your master's will do nothing to change the fact that you are switching programs.  There is no reason to defer.


Should I ask for a deferment so I can finish my masters?


No, this is not a credible reason to defer unless the masters is required for admission to the new program.


Should I ask the new departments I have offer from if they allow me
to go back and finish my current program and defer my enrollment in
their program until next year, or should I accpet the offer, and then
ask them?


An important rule of negotiation is that you negotiate before you agree.  Accepting and then negotiating is dishonest, and more likely to fail.


Does it make sense to choose based on whether they allow me to do that or not? (and so, ask now)


No, enroll in the best PhD program you can.