Now, I am not a lawyer and not a CPA. However, I have seen several cases of "less-than-honest" businesspeople who have all but everted their tax responsibility. Employer's taxes are a very tricky situation because it is not his money that he is not paying. . . it is the employee's money for federal, state, local, and retirement taxes that he is not paying. If your partner had other partners as part of his S corp then they should also be responsible for a portion of the tax liability. In my experience, the IRS is rather cooperative if you go to them with an agreement. It sounds like your partner may not understand his obligation to his employees and ultimately us as taxpayers, for we end up footing his bill by paying higher taxes.
Now as far as the personal liability, I have seen the IRS TRY to levy someone's assets when they are in default of 941 taxes and were in an S corp. They were unsucessful because the liability is usually somewhat deferred in an S corp. Make sure that this ALL happened while he was an S corp. Otherwise, the rules change.
The LLC. . I have to admit I have very limited experience and limited knowledge about those. However, I do know that it is very hard to attack a person within one. That is why they are termed Limited Liability Corporations.
My advice. . . .this guy may be a good guy, but in my experience ALL of the people that I have seen who have avoided paying their employers taxes have also avoided paying other things and were going downhill financially. I don't know him or you, but the word of caution that I send to you is. . get out now before you find out more bad information.
