I am always intrigued by the semantics of tax return preparation.  When I do a joint return, I think of it as one for "my clients," plural, which reminds me that I have a conflict of interest and usually can't work for either of them when they divorce.  When someone else mentions a return for a "client," I assume there is just one of them.  But then, some of "my clients" who are parents of the same offspring will talk about "my kid," as if the spouse has nothing to do with it.