I question whether such a move would be constitutional. Yes, the states have the power to regulate elections, which includes ballot access. However, this does not accomplish any legitimate interest in regulating ballot access. This only establishes a political test, with the effect of secretly creating an additional qualification for an elected federal office. And the states have no power to institute new or additional qualifications for elected federal offices.
It will have to be decided by the SCOTUS. I am not sure showing your taxes is a qualification though, is it inherently different than making someone gather thousands and thousands of signatures?
It doesn't have to be and maybe we should welcome the change in attitude towards ballot access seem to embrace. If we are going to start deciding it's okay to adjust state rules for ballot access or voting on political preferences, the Democrats would be wise to figure out they don't have the states necessary to accomplish crap, and will do more to hurt themselves opening that door than anything else.
But they may get a clue when they lose so bad in 2020 they have to address the fact that their fricken nonsense is a bit too far for even the most uninformed voter. They have yet to recognize that it's not just Republicans, Conservative or Libertarians that are getting sick and tired of their bullshit dicking around.