I know that treatment of both spouses as one is provided for explicitly with respect to certain deductions.
I also know they aren't always treated this way. For example, I know that when one spouse pays rent to the other for property they own jointly, the payor can deduct half of the rents paid. I also know that attribution of net self-employment income to one spouse or another is important.
What I don't know is which way to lean when things aren't so clear. When I read "the taxpayer" in some Code section or another, should I assume the provision applies separately to each party to a joint return absent evidence to the contrary? Or should I assume that "the taxpayer" is a fictional entity consisting of both spouses, unless context clearly indicates otherwise?
In asking this question, I am contemplating payments and other transactions that one spouse or another enters into. For example, health insurance premiums. In the case of the SEHI deduction, does it matter who pays them?