@dmertz wrote:
Tax withholding is 30% on the potentially taxable portion of a 401(k) or IRA distribution paid to an nonresident alien. Tax liability for a nonresident alien is determined on Form 1040-NR.
I believe that IRA and 401k withdrawals fall under the category of income "not effectively connected" with a trade or business because it is Fixed, determinable, annual, or periodical (FDAP) income.
https://www.irs.gov/individuals/international-taxpayers/fixed-determinable-annual-or-periodical-fdap...
FDAP income is taxed at a flat rate of 30% (not just withheld) unless there is a tax treaty with the other country that specifies differently. See Form 1040-NR Schedule NEC.
