HOW TO REPORT BUSINESS FOR NOT PAYING TAXES?

I have the crony who owns the tiny business. She takes credit label payments as well as charges taxation upon the equipment sold. I not long ago found out she has not finished taxes for the commercial operation or herself, in years. She had the store for about 6 yrs, the initial year she filed taxes though not given then. I dont consider this is right. How do I inform this? And what would occur to her?
Do not write foolish comments about how I’m not the great crony for stating her. READ THE QUESTION!