What mistakes? The IRS never makes mistakes. You just do not understand their interpretation of the tax code. I know from experience that their interpretation of the tax code is as fickle as their moods.
It took me one hour (fast for them) to straighten out a client's account in Mississippi who had paid all their income taxes in 2007 in full and on time.
When the geniuses couldn't find an account with her name on it they invented one. The payments were hanging out in an account one digit off from her social security number and they had placed a lien on that account! Don't ask me who received the lien for a tax overpayment but it wasn't my client although she did get a notice. WHAT A MESS!
The first person I spoke to over a month ago named Linda told me that she would fix it and call me back. Well, she didn't. I called again and got another Linda who eventually did fix it but she said the first so-called Linda must have used her name because she was the only Linda in her department. It is so comforting to know there is a fraud working there!/s