You're officially going to be a member of the Class of 20XX! The deposit is down, you've obsessively reviewed the timeline for admission and fantasized about electives and going out in your new city.
So how do you tell your boss? There is of course no true right way, but there are some wrong ways. You ALWAYS want to maintain a good relationship with your former employer for many reasons, namely the world is extremely small. That is perhaps the biggest takeaway from business school, you never who you will run into again, or who will have influence over your future in some random way- keep things cordial.
Your resignation letter can certainly have some variation of "I have grow immensely in this role with our team and your leadership." Maybe a little bit of "I am excited about the next chapter of my professional career and have decided to pursue my MBA at XYZ." Oh and maybe close with "While my last day will be XX, I intend to provide my full support for the transition and complete all projects currently in the pipeline."
Suggestions for next steps while still collecting a paycheck include:
Map out your planned exit and communicate it clearly
Depending on the round you applied, admission decisions begin trickling in between the winter and spring with enrollment kicking off in August. If you decide you want to travel all summer long, let your boss know you want your last day to be in May and begin succession planning. Tackle any big projects you may have lined up and be sure to leave your role better than when you first entered it
If you plan to work up until you fly out for orientation do your best to give it your 100% every day
Some of us in more financially precarious circumstances may choose to keep working up until we need to leave. If that is the case, you can certainly give the customary 2 weeks notice, though more notice is preferred. Either way, give it your all up until you depart- don't day dream too much, stay focused on the work you need to do and show up
If you plan to take lengthy breaks between admission and starting school, give your boss a heads up