thats a good question. Of course, Americans do not need a visa to visit mexico - just a valid passport. you fill out the FMT at immigration on the way in and give them the stub on the way out.

But conducting legal/personal business is something else. This past summer I tried to open a bank account with my Mexican citizen wife and the bank said I couldnt be an owner or signer on an account without having residency in the country (basically, the visa you talked about). Same thing with being on a credit card from a Mexican bank.

I didnt do anymore follow-up / research on this and your question reminds me I need to do so.

On the other hand, I encountered no bureaucratic problems while in Mexico when obtaining my son's Mexican birth certificate and passport (and renewal of his passport) with no documents other than my US passport and showing my FMT stub that I was legally in the country. My signatures on the various bureaucratic forms needed no special "authorization" or status documents.

So it would appear there are different rules for different types of "business".

I wish I could be more helpful. Perhaps J Diver has some info on this. You might also check Mexico Mike's webpage http://www.mexicomike.com/index.html You should also contact the US Embassy in Mexico or any of the consulates - they should give definitive info.

Please be sure report back what you find out - I am very interested to learn about this, too.