thanks for your reply and link. The documentation does not give specific country-specific obligations, just says "generally". I am preparing a streamlined return, so my pension reported annually is only from 2016 and 2017, so in my specific case, it does make a difference on the value of the considered distribution

the link above is from 2012, but i found additional information in the 2016 US revised model income treaty that the transfer to a tax deferred account within the same country should not be taxable.


https://www.treasury.gov/resource-ce...Model-2016.pdf

Article 17
PENSIONS, SOCIAL SECURITY, ANNUITIES,
ALIMONY, AND CHILD SUPPORT

2. b) Where a citizen of the United States who is a resident of __________ is a member
or beneficiary of, or participant in, a pension fund established in __________, the United States may not tax the income earned by the pension fund as income of the individual unless, and then only to the extent that, it is paid to, or for the benefit of, that individual from the pension fund (and not transferred to another pension fund established in __________ in a transfer that qualifies as a tax-deferred transfer under the laws of__________). In such case, the provisions of paragraph 1 of this Article, which generally is subject to paragraph 4 of Article 1 (General Scope), shall apply.