Is it illegal to rent a bedroom that isn't on the county records?

[Anne Rank]

I am currently in escrow on my first rental property. I discovered the house I am buying was falsely advertised as a 3-2, county records show it's only a 2-2. One of the "bedrooms" in the basement doesn't have a closet attached, but there is one right next to the bedroom in the hallway, so I think that is the issue. Would it be illegal to advertise and rent the house out as a 3-2? I plan on adding an egress windows to the basement rooms before renting. The basement was finished in the 60s. I would appreciate any insights, thanks!