The classic arrangement is salary plus expenses and/or an overseas bonus. Work outside the U.S.A. over a certain period of time exempts one from U.S. income tax. However, at that time you are considered a resident of that country and are liable to their tax structure. In most cases, the foreign government tax rate is much higher than that of the U.S.A. at our levels of income. Bottom line tax-wise is that there is no free ride. You have to pay taxes to someone.

Having no visible income then signing a tax form prepared by someone else stinks. I don't care how reputable this "corporation" is, they are asking her to do something deniable. She has no recourse if they get caught dirty and choose to say "Huh? We assumed she was filing taxes as required."

Sounds like the corporate entity is a volunteer organization. If I had to guess, I would say American Red Cross, her assignment being to International Red Cross which is headquartered in Switzerland.

I would not do it. Red Cross (if it is them) has a paid cadre and could do it cleanly and on the up-and-up if they simply hired her. BTW, I was a Red Cross disaster services volunteer and I think the management is terrible so maybe I have a bias and maybe it isn't Red Cross at all.