I lived in two places last year, one inside the US and one outside the US (where I live now), but I wouldn't use either as a permanent mailing address.
I've been looking for clarification about what is the most appropriate address to use and why, and I'm left with some questions:
Thanks!
The address on your tax return is where they will send correspondence, including refund checks.
If you don't want to use either your old U.S. address or your current foreign address as a permanent mailing address, you might want to use a mailing service, or a friend/family member that you trust.
Occasionally the IRS or a state will question your residency based on the address used, though the IRS might figure it out if you file Form 2555 to claim the Foreign Earned Income Exclusion. Some states will wonder why you're not filing resident returns if the mailing address for you is in that state. If that happens, (1) make sure it's not a domicile state and you really aren't a resident, and (2) send them a letter saying that you are living overseas and that the address they have is only your mailing address, and give them your foreign residence address.
If it is similar to Australian Tax law, then I would say it would be mainly for correspondence, for sending you mail and in case they need to contact you regarding your taxes. Correct me if I am wrong, but State taxes would only apply if you owned the place not renting it.
