Legal Question in Real Estate Law in California

You'd be personally liable if you sign a guarantee or sign a document in which you make yourself personally liable. Normally, contracts are signed by corporations on behalf of the corporation, but that does not make the individual signing the document personally liable.

The IRS has special powers to pierce the corporate veil that regular litigants do not. That does not mean, however, that it applies in your case. This is not a situation to be dealt with in an internet Q&A. Go talk to a lawyer in person before you sign anything. Do not take the word of some loan broker.

The special powers of the IRS apply to persons (shareholders or officers) who are active in the corporation and participate in allocating its resources. When, for example, taxes withheld from employees are not remitted to the IRS, it can assess a so-called "100% penalty" against the officer or employee who has authority over the company's cash disbursements. They'll look to see who's been signing checks, and go after that person individually. In your case, if you are a shareholder only, not active in corporate affairs, I doubt you have exposure of this kind. See Internal Revenue Code section 6672 or go on-line and search for IRS and "100% penalty."

Possibly a greater risk for you is that the business may not, after all, be incorporated. The loan broker may be pointing out something you're not aware of (and should be).

I'd suggest talking directly with an attorney with corporate and IRS experience, and also have another chat with the loan broker to determine whether (a) he is giving you a warning that all is not as you thought with the business, or (b) the loan broker doesn't understand the difference between a "shareholder" (of a corporation) and an owner of, say, a partnership or proprietorship. In any event, the broker's use of terminology doesn't add up for me.