Schedule E - filing as non-passive income

[Pam Smith]

Hi all-

I was reading one of the blog posts on the Short Term Shop blog about Schedule E vs C, passive vs non-passive. In the blog, they reference, "According to Treasury regulations, vacation rental owners who rent their property out for seven days or less on average do not fall under standard rental regulations, meaning that they'll be able to file their income as non-passive instead, without worrying about qualifying for professional status." 

Does anybody know the exact Treasury regulation that I can reference to my CPA. He's not bought into this. I know I can switch my CPA but we've been with him for a long time and he's been good thus far. Does a ton of commercial real estate, very few short-term rentals.

Thanks!