Leaving Japan as a PR – various tax questions

Hi all! I have a wealth of questions that I would like some advice on. I am a non-US citizen considering a move to the US for work (different company) whilst a PR in Japan. I want to maintain my PR status without paying taxes in Japan whilst I am away, and then at some point come back (and not bind myself to owing the US taxes for the rest of my life). My understanding is to do this I just need to get a 5 year re-entry permit in JP, and not leave the US with a green card. Is it as simple as this?

If so, then I have some additional questions:

  1. Is filing the 海外転出届 the correct form for me to fill?

  2. Apart from switching to National Insurance and Pension for the short time between resigning and leaving Japan, and paying off all of my 2024-calculated residence tax, is there anything else I would need to do?

  3. How _do_ I pay off all of my residence tax, will this be through my current employer (who currently takes it out of my month-to-month salary), or through the tax office?

  4. If I leave by the end of the year, I understand I won't owe residential taxes next year which seems like a massive 10% saving. I assume though that this adjusts my furusato nozei "allowance" – is there a calculator that can help me _simulate_ my new allowance?

  5. When I leave the airport on my flight to the US, or wherever, I'll tick the "coming back within 5 years" box on my departure form. Will I need to answer any questions at the immigration counter, and if so is my reason for leaving going to be scrutinised?]

  6. I am aware of needing to close out PFIC-subject ETFs/mutual funds, but I have also been told that mutual funds that track completely non-US based indices are also taxed aggressively. If this is the case, what _can_ I leave in my securities accounts? Should I sell up everything and just buy individual stocks in my NISA before it "freezes"?

  7. On the note of selling.. if there's a week between giving up my JP tax residency and getting US residency, am I able to sell my crypto, stocks etc during that week and owe no capital gains anywhere (or income tax for crypto)? I know I would not be a US tax resident before the date I move if I move late in the year. This seems like a major tax break, essentially allowing me to reset my cost bases on everything… surely not?

And anything else that you are are aware of that could be helpful to know… I would be extremely grateful.

If I do make this choice I will of course hire a tax expert, but thought I would see what the community can share first. Thank you!

by ViralRiver