@aherasimovich wrote:
Am I correct that at the very least they should stop counting their contribution as imputed income as of May 17?
I don't believe this applies in your case because your spouse is not on your health plan as a spouse. Per section 125, your spouse can only join your plan as a spouse using the 30 day rule or during the open enrollment period.
https://www.law.cornell.edu/cfr/text/26/1.125-4
If you think there is a conflict between section 106 and section 125 that should be resolved in your favor, you need to talk to an attorney or tax accountant. I have not been able to find any documentation one way or the other of what is supposed to happen if you marry your domestic partner and miss the 30 day window.
