Working for Consulate / Tax Return

[nisaruz]

Hi!
My husband has GC and since july 08 he works for Brazilian Consulate. I was looking for some answer how to fill the Tax return but I did not find answer. Also I contact IRS and they just hang up on me and answer something that I did not ask. Than I wrote them email specially sent to embassy@irs and I did not get any answer . Even though I got message that the email was read.
Now to the problem.
I know that If he doesn't wanna loose his GC he has to give up his diplomatic rights... and fill out the form I-508.
But it says that he may get Tax exemption anyways( he pays already taxes in Brazil).
But how to find out? In the consulate they don't know. And they don't really care because almost anybody there has GC. The IRS just doesn't give the answer.
This is the only thing I found: Question nr.28
http://www.irs.gov/businesses/small/international/article/0,,id=164365,00.html#2
So, what to do now?
Can somebody help?

And one more thing. What about Social Security coverage? I just do not understand. Should he pay it or not. He would like to...

 

[nkm-oct23]

US law requires green card holders to file tax returns as a US resident. If he works for the govt. of Brazil in the US then they are supposed to deduct SS taxes. If they don't then your husband has to pay it at the time of tax filing.

If he also pays taxes to Brazil he may be able to offset that tax against any taxes that are due to IRS by claiming foreign tax credit on form 1040.