Until you receive a Bachelors your legal residency is that of your parents. Unless you work full time for at least one year and not go to school, enlist in the military or get married. As long as your parents claim you as a dependent on the 1040 you are bound to their residency.
When my daughter applied to law school in AZ she was considered an out-of-state student, because we are FL. Even though she lived in AZ for 4yrs as an undergrad, she is paying Out of State tutition to AZ again for law school.
Going to SA is the same as enlisting, you are no longer a dependent on your parents tax form.
OK. I just spoke to the nice lady in the Nominations Office of the USNA. Here's the story.
As she said, "Title 10" requires that service academy nominations come the MOCs for where you are domiciled. However, Title 10 DOES NOT define "domicile". USNA follows Title 10, which means they do not apply a rigid test for domicile.
So the USNA uses some loose rules for giving candidates advice about domicile. They don't even have these rules written down since they are informal. However, ultimately, it is up to the individual MOC to define domicile. As the woman said, some MOC insist that your domicile is where you or your parent/guardian pay taxes and therefore they will require an affadavit that you are paying taxes in their district. Others use a much looser definition of domicile.
I specifically asked about Congressman Van Hollen's definition of domicile (including 183 days, etc.) and she said that the USNA does not review individual MOC's definitions of domicile- if that's what he requires, then that is what you have to fit in order to get his nomination. The nomination office does try to stay on top of what the different MOC require though. She gave me the example of the 2 former senators from Maryland - she said that they used to make things a little tougher by requiring taxation affidavits, but the current senators don't require that.
The main USNA rule is that you can only apply for nominations from one district/state, you have to meet the specific MOC's rules for domicile or they don't view you as a constituent and won't want to nominate you. If you fit fit the MOC's rules, then you meet the requirement of Title 10.
She suggested the following things as stuff the MOC typically consider in deciding if you are domiciled in their district and therefore a constituent:
1. is your mailing address the same as your physical address? yes- good, no- bad.
2. are you physically living in that district/state?
3. are you or your parents paying taxes in that district/state?
4. are you (or if under 18, your parents) registered to vote in that district/state?
5. if you have a car, is it registered in that district/state?
6. do you have a driver's license in that state? what does your driver's license say your address is.
7. if you have more than one parent or guardian, do they both physically live in the same address?
one thing she specifically said that shouldn't matter is your domicile is different that where your high school is located if you happen to be going off to college. Being domiciled in a different district than your high school is a problem if you are applying to USNA from highschool however.
The USNA deals with borderline cases where candidates have problems with domicile for different reasons, and in these cases, the USNA nominations office tries to give advice to a candidate. Mostly the advice includes things like "get a drivers license" and "register to vote". She said some of the trickiest situations occur when candidates or their parents are paying state taxes in a different district/state then they physically live, and if the local MOC uses a taxation test for domicile. In those cases, she recommends using the taxation location as a domicile, if possible, and switch over other things (such as driver's licenses) to the taxation location.
apparently, issues with domicile more often come up with prior service applicants who can domicile themselves almost anywhere, but applicants from high school and college are usually, not always, domiciled with their parents.
Bottom line though is, if you want a nomination from an MOC, and you have any questions about whether they might consider you domiciled in their district, contact the MOC and get their rules concerning domicile.
So my interpretation based on this is that when you look at different MOC's nominating applications and one just says you have to be a "legal resident" and asks for your address, and another (like Congressman Van Hollen) makes you get a notarized an affidavit, this is not because some of these different MOC's have the wrong understanding of what it means to be domiciled in a district. it's because each MOC has his own definition and the USNA is OK with it, as long as a candidate doesn't use these different rules to apply for nominations in more than one district.
i hope this will help anyone else wondering about domicile- contact the MOC and get their rules!