What factors go into choosing residency?
A couple of thoughts. Tax benefits are the usual reasons to decide on one residency or another. International tax law is complex, and it's probably best to consult a professional. Certainly without knowing which the other country is I would not want to hazard a guess. If he is really not going to be taxed on the other country, residing there would seem sensible. But... In Canada residency for tax purposes is established for an entire year. If you are resident for more than six months your salary for the year is taxable. Conversely if you are present for less than six months you are not taxable. (This may have changed - it's been twenty years since I did this.) The other issue is healthcare. If you are not resident in Ontario you are not eligible for free healthcare, I believe. He might have to purchase supplemental insurance if he returns occasionally.
Without knowing actual numbers it's tough to say.  Personally, I would pay off the car then, going forward, use the money that would have been paid on your car note toward your mortgage.  I always think of things in the worst possible scenario.  It's easier, and faster, to repossess a car than to foreclose on real estate.  Also, in an emergency situation, depleting your fund for your car loan and your mortgage would be significantly more detrimental than only paying a mortgage with a car owned outright.  Fewer obligations means fewer things to draw down your funds in an emergency. Whether the tax deductability of the mortgage interest outweighs the lower rate on your car loan will depend on a lot of factors that haven't been shared.  I think it's safe to assume with only 1% of separation the real difference isn't significant.  I think when determining which credit cards to pay off, choosing the one with the highest rate is smart.  But that's not the situation you're in. If you don't have foreclosure concerns I'd still pay off the car then start investing. Assuming you're in the United States, then International Equity is an equity from a different country.  These stocks or stock funds (which reside in a foreign country) are broken out seperately becuase they are typically influenced by a different set of factors than equities in the United States: foreign currency swings, regional events and politics of various countries. Per the IRS instructions on filing as Head of Household as a Citizen Living Abroad, if you choose to file only your own taxes, and you qualify for Head of Household without them, the IRS does not consider you married: If you are a U.S. citizen married to a nonresident alien you may qualify to use the head of household tax rates. You are considered unmarried for head of household purposes if your spouse was a nonresident alien at any time during the year and you do not choose to treat your nonresident spouse as a resident alien. However, your spouse is not a qualifying person for head of household purposes. You must have another qualifying person and meet the other tests to be eligible to file as a head of household. As such, you could file as Married Filing Separately (if you have no children) or Head of Household (if you have one or more children, a parent, etc. for whom you paid more than half of their upkeep - see the document for more information).   You also may choose to file as Married Filing Jointly, if it benefits you to do so (it may, if she earns much less than you).  See the IRS document Nonresident Spouse Treated As Resident for more information.  If you choose to treat her as a resident, then you must declare her worldwide income.  In some circumstances this will be beneficial for you, if you earn substantially more than her and it lowers your tax rate overall to do so.  Married Filing Separately severely limits your ability to take some deductions and credits, so it's well worth seeing which is better. "If you live outside the US, then you probably need to deal with foreign tax credits, foreign income exclusions, FBAR forms (you probably have bank account balances enough for the 10K threshold) , various monsters the Congress enacted against you like form 8939 (if you have enough banking and investment accounts), form 3520 (if you have a IRA-like local pension), form 5471 (if you have a stake in a foreign business), form 8833 (if you have treaty claims) etc ect - that's just what I had the pleasure of coming across, there's more. TurboTax/H&R Block At Home/etc/etc are not for you. These programs are developed for a ""mainstream"" American citizen and resident who has nothing, or practically nothing, abroad. They may support the FBAR/FATCA forms (IIRC H&R Block has a problem with Fatca, didn't check if they fixed it for 2013. Heard reports that TurboTax support is not perfect as well), but nothing more than that. If you know the stuff well enough to fill the forms manually - go for it (I'm not sure they even provide all these forms in the software though). Now, specifically to your questions: Turbo tax doesn't seem to like the fact that my wife is a foreigner   and doesn't have a social security number. It keeps bugging me to   input a valid Ssn for her. I input all zeros for now. Not sure what to   do. No, you cannot do that. You need to think whether you even want to include your wife in the return. Does she have income? Do you want to pay US taxes on her income? If she's not a US citizen/green card holder, why would you want that? Consider it again. If you decide to include here after all - you have to get an ITIN for her (instead of SSN). If you hire a professional to do your taxes, that professional will also guide you through the ITIN process. Turbo tax forces me to fill out a 29something form that establishes   bonafide residency. Is this really necessary? Again in here it bugs me   about wife's Ssn Form 2555 probably. Yes, it is, and yes, you have to have a ITIN for your wife if she's included. My previous state is California, and for my present state I input   Foreign. When I get to the state tax portion turbo doesn't seem to   realize that I have input foreign and it wants me to choose a valid   state. However I think my first question is do i have to file a   California tax now that I am not it's resident anymore? I do not have   any assets in California. No house, no phone bill etc If you're not a resident in California, then why would you file? But you might be a partial resident, if you lived in CA part of the year. If so, you need to file 540NR for the part of the year you were a resident. If you have a better way to file tax based on this situation could you   please share with me? As I said - hire a professional, preferably one that practices in your country of residence and knows the provisions of that country's tax treaty with the US. You can also hire a professional in the US, but get a good one, that specializes on expats." But the benefits in EU countries are better. I don't see a reason to go to the US for an employment, especially if there's a clock of 6 years running on it.   I don't know if I can ever explain that to anyone, but moving 8,000 miles to a different continent that feels like a third world country with crazy shootings and shitty healthcare, and than when you finally get used to it and get settled in you get kicked out and besides illegally getting into a greencard marriage you can't stay. they would deport you like a criminal after paying taxes for 6 years.  so yeah, in my personal opinion and pretty much every former H1b holder I know, it's not worth it as long as there's a time limit. Hmmm. I assume to be accepted into a PhD/masters program without a masters one would have to be an absolute stud though. I come from a school that isn't too hot on academics. It is a large public research institution, but it's not a UT or Notre Dame type school. I guess I should talk to my professors about the whole process. What makes it hard is that you're making this decision now, when you've already made decisions over the years going in a different route. I've noticed this recently w/some of my friends, that decisions, even small ones, over the years now come back to bite them b/c they didn't have a long term view. Now in early 30's they are constrained by choices throughout their 20's. Unfortunately, most people aren't equipped to make good decisions earlier, which hurts them later. So making such a change in lifestyle becomes harder.  So while it can be done, it's going to take some hard decisions. Just remember, children are a great reward, and a great sacrifice. Since we are talking about retirement accounts, I wouldn't worry too much about what your income will be in the next 10 years or so. I'd recommend basing your contributions primarily on what your likely income/tax bracket at or near retirement age will be compared to 25% today. I don't think that optimizing for the next three years will make a significant difference, given the uncertainty of the tax code as well as your income in the future. However, it may make a difference to your planning whether you are going to grad school for an M.D. compared to an MSW, however, as to what your expected income/tax bracket will be.