I don't think it's a fox, I think you either have a color-phase Coyote, or an all-American "Best Friend." Snow looks to be a few inches deep back where it's at, which makes the legs look shorter than a coyote usually looks, but the TAIL is not what most FOX tails look like around here. I'd bet it's a 'Yote or a Dog.
I'm just not seeing THIS tail on that animal in that pic.