Another point of view.  Remember 'assignment of income?'

I have a big brokerage account.  I put my GF as co-owner.  [Don't tell my wife!]

I did not file 709.  Maybe GF does not even know.

I go back to: "Whose $$ is it?"  If they truly own it equally, report income equally.  But I do not see how you can shift income to whomever wants it each year.