will the homeowner get in trouble? back taxes and fines or ??

I'm just curious - came across a house that's apparently been appraised at its original size but they've been busy changing it all around since they bought it 10 years ago.

If proper permits were pulled the tax assesor should have gone out immediatley to asses an updated value.

Not having changed assesments would be a red flag as to whether proper permits and building code was followed.

As far as fees and fines that goes by local jurisdiction on how they operate so can't answer that.