Sorry, but I may have stated my question incorrectly. My question is not about spending the money in an HSA. Rather, it's about who can deduct contributions to a HSA.
It could also be that I have an incorrect understanding of the rules of filing "jointly." Maybe an example would display my lack of understanding of the matter and clarify the question.
If I as a single person have an HSA, I believe that I can deduct contributions made to my HSA, regardless of the source of the funds. Conversely, if I made a contribution to a friends HSA, I cannot deduct those funds from my taxes even though the funds came from me. Why? The HSA is in my friend's name, not mine.
Now, my friend is married. They opened a HSA in the name of his wife, and only his wife. Why? Because only she has a HDHP. I understand that the funds can be SPENT on the husband for medical purposes tax free even if though he is not covered by a HDHP. However, can the husband make a contribution to the wife's HSA and deduct the contributed funds from his taxes? Does the fact that they are married change the rules? Does the fact that they are filing jointly change the rules?