When I made my applications last year, I did to two schools in the US. I was shortlisted for interview at both schools. School A and School B. School A were more interactive than B and I got an offer (which I accepted). On the day I got my I-20 document from school A, I got a mail from school B regarding an offer. Both offers are funded and with Assistantship.
How permissible and ethical is it that I change/decline my offer to school A?
Personally, both programs are a perfect fit my academic career. The only nuance, for me, is that school B pays more than School A.