"I HAVE a nephew in Ireland who would like to live in the U.S. My sister (his mother) says if I complete a form that says I will vouch for him financially that he will be able to come here. Is this true? What is it that I have to do?"

AFFIDAVITS of financial support are a required component of most applications for green cards, including all relative-based ones, but there are also several other matters that need to be addressed and your question doesn't provide enough information to do so. We'll quickly start at the beginning.

All potential immigrants to the U.S. need a qualified sponsor, either a U.S. relative or employer. You will not be able to sponsor your nephew as there is no provision in immigration law for doing so. (The only U.S. citizen relatives who can act as sponsors are spouses, parents, children over 21 years of age and siblings.)

Does your nephew have another method of family sponsorship that you didn't mention? In that case you would be able to act as a co-sponsor on his affidavit of support if the primary sponsor didn't have sufficient financial means for doing so.

The affidavit of support is a legally binding agreement that the sponsor will make financial provisions for the new immigrant in the case that the person requires public assistance. The agency providing the assistance can by law ask the affidavit sponsor to cover the charges, so the document is a serious one.

The financial commitment ends either when the immigrant becomes a U.S. citizen, or is credited with 40 quarters (10 years) of employment. Visit http://www.uscis.gov/files/article/G4.pdf for further information.