To my knowledge, there isn’t a “Bathroom Requirement Cop” that goes around trying to catch non-compliant bathrooms.
However, if you remodel your bathroom (with or without a Permit) you’ll need to comply with the then current code. The consequences of non-compliance can be severe: 1) If someone has an accident because of something you did (or didn’t do), your insurance may not cover you, 2) If your house burns down your insurance may not cover the cost to re-build a non-compliant structure, and 3) when you sell your house, you’d better disclose the non-compliance, or you’ll pay for a giant remodel.
1) As my accountant explained to me, make sure you have insurance in effect or if there’s an accident, I may be paying this person a check each month until they graduate from Harvard.
2) Generally, Fire insurance is a “Build-Back”. When you want to fix the bathroom problem, they may say the policy is void. (As you can imagine, insurance companies don’t like insuring non-compliant structures.)
3) I testify on behalf of buyers “who were mis-led” and want restitution. Beware as a seller.
The good news, there’s a Chapter in the Code that allows existing conditions to remain, except for A) lack of smoke detectors for bedrooms, and B) non-tempered glass in sliding doors, windows within 18” of the floor or within 12” of a door. (See ICC Chapter 34.)
So, if you’re thinking of working on your bathroom and do NOT want the Building Department involved, there is a way. A little known fact, the Code is divided into two categories: 1) Alterations, Repairs and Additions, and 2) Maintenance. Nowhere in the Code do you need a Permit for “Maintenance.”
Maintenance is for: 1) non-structural, 2) no change of occupancy classification, 3) no change in exiting requirements, and 4) no alteration, repair or addition, of course.
I’d still ask the local Building Official if it’s Maintenance before you start, because someone may look in the window and see construction and turn you in because you parked in front of their house 3 years ago and “will show you what’s-what.
If that still doesn’t work for you and the Building Official thinks you should obtain a permit and comply with all requirements, there is an Appeals Board in each State. They generally meet at least twice a year, depending on number of applicants. So, plan ahead. (Tip: offer an alternate idea to “nearly comply.”