No idea about FX but I can answer Q2.
Sterk wrote: ↑Sun Mar 03, 2024 5:30 pm
am I required to fill out the section on the 特定口座 as well or can I skip it as any due taxes on that account were already withheld at the source? I thought this were the case, but I am slightly confused. If I try to load the .xml transaction data I got from Rakuten Securities into the section for separate taxation the projected tax to pay slightly increases. But if anything I would have expected a very slight deduction due to credit on some foreign dividends (which appear as 外国税額控除等 after loading the data file).
You can leave it. Technically it's considered as "separately taxed as source". Some info here:
https://retirewiki.jp/wiki/Income_Tax
You're right that you're foregoing a deduction by doing that though, as you will have also paid some US witholding tax on the dividends, which you can put into the calculation for the foreign dividend deduction. However, in order to do that you need to declare the dividends (using the XML file) on the tax return. You can choose to keep it as separate taxation (probably better) or lump it in with aggregate taxation (better in some circumstances but I'm guessing not yours).
The way it works:
1) import the XML file to have the income and witheld yen show up, assign it as separate taxation (taxed at the same rate as the tokutei kouza). This will cause you to pay slightly more tax, because you'll be paying JP tax on the full dividend, not the dividend less US tax.
2) Make sure the already witheld Japanese tax also shows up in the witheld tax section so you get a tax credit for that amount.
3) You need to manually enter the details to claim the foreign tax deduction. It should cause you to get a tax credit equal to the amount of US tax you paid, but it might be less due to the credit being capped to a proportion of your tax bill (and due to this, any credit that you couldn't apply is rolled over in various complex ways).
I was actually planning to write a guide about this on the wiki but life happened and I didn't get around to it. I don't think there's a good English guide but there are some in Japanese.
Basically I think you should look at how much US witholding tax you paid on the dividends (it's listed on the human readable 年間特定口座取引報告書 that accompanies the XML file) and decide if reporting it to claim the foreign tax deduction is worth your time. In my case it's not, but I do it anyway.
There's a good overview here but that also doesn't tell you how to actually claim the deduction.
https://www.reddit.com/r/JapanFinance/c ... ax_credit/