I will be applying to colleges soon in the UC system: University of California. I have lived in California my entire life but my dad is in the military and both of my parents are registered as residents of Tennessee. Am I a California resident or a Tennessee resident? If I am a resident of Tennessee, does that mean I have to pay out-of-state tuition? have proof of residence here for the past 15 years. My dad still pays taxes for Tennessee and neither of my parents can vote in California because they are Tennessee residents.
You’re a resident of both TN and CA for tuition purposes. https://www.military.com/paycheck-chronicles/2015/11/12/in-state-tuition-rules-for-military-families
Yeah, you’re a resident of both states but the human always chooses his homeland 
I would contact someone in one of the UCs to assess your situation. The rules state that you must not only be a resident for more than a year (which you have) but also demonstrate that you intend to stay in California, which is nebulous based on what you said.
Criteria related to Military families on page 21-22 of this document: https://www.ucop.edu/general-counsel/_files/ed-affairs/uc-residence-policy.pdf#page=11 . I feel, in general, that if you attended and graduated from a California high school, no one would question your residency. But this document has the official policy.
@ProfessorPlum168 I do intend to stay in California and I’m not planning on leaving. How would I demonstrate intent to stay?
Based on the document that @momneedscoffee linked, it sounds like you would be considered a resident for tuition purposes for UC. But yeah check with a financial aid person at one of the UCs just to make sure.
@medigull to show that you intend to stay in California would be as simple as things like getting a California drivers license or registering to vote in California.
If you graduate from a California high school, and your parent is based in California, you should be able to pay in state rates for tuition, but that doesn’t mean it includes housing.
Because they don’t pay California taxes, you won’t qualify for CalGrants.
Check with each UC to confirm your tuition.
Your parents can also contact the VA offices to getr more info about any military benefits for you.
In addition to the military related provisions, you may also qualify for the equivalent of in state tuition and financial aid through AB540 provisions if you graduate high school in California after enough years of attendance.
Will you be graduating from a CA high school?
I’m a little confused…are you living in TN…or CA?
Is your dad going to transfer GI Bill education benefits to you? He must do so while active duty.
If your parents aren’t Calif residents, then it sounds like you won’t qualify for a Cal Grant. Are your parents aware of that?
If you graduate from a CA high school and if you attended three years of high school in CA (in any order) then you get in-state tuition regardless of your parents if you file an AB 540 request. http://admission.universityofcalifornia.edu/paying-for-uc/tuition-and-cost/ab540/index.html
Yes, but does that qualify you for a Cal Grant if your parents aren’t residents? Or do you only get instate rates?
http://ab540.com/Paying-for-College.html indicates that AB540 students are eligible for state financial aid.
Main frst thing is read all these links. Some are long, but it’s not a tough read. Do this before calling.