410.392—Domicile.
(a)
For purposes of this subpart C, the term domicile means the place of an individual's true, fixed, and permanent home to which, whenever he is absent, he has the intention of returning.
(c)
The domicile or a change in domicile of a beneficiary or other individual is determined with respect to the period or periods of time as to which the issue of domicile is material.
(d)
If an individual was not domiciled in any State at the pertinent time, the law of the District of Columbia is applied as if such individual were then domiciled there.