Many thanks for your effort at help but as a retired international (ie cross-border) tax lawyer I have read the statute, checked RIA, and analyzed the IRS non-binding public advice.
We are not talking about a dependent. Kiddo is NRA and doesn’t live in US, Mexico or Canada. That affects dependent status not the right of the grandparent (etc) housing and supporting him/her to claim HoH status. I’ve been in Tax Court before. IRS settles “on the courthouse steps” when they’re wrong. Or Through CDP these days. The dependency issue is a red herring. Kiddo’s mom lives with me and is a student.
It is equally likely that my $4k is held up by the tax treaty provision (art 18-19) that makes my federal pension taxable solely by the IRS and my Social Security solely by HMRC. The Saving Clause doesn’t change that.
My guess is that in the fullness of time the IRS will ask for proof of common residency and proof of more than 50% support. Those are issues of fact and proofs could have been supplied with the 1040. I will do that for 2022. Unfortunately as kiddo has no SSN my return has to be paper-filed.
