As she is a GC holding US resident she has to complete a tax return, so this all should be on the tax documents you use for the the details. What you had said is that she is not reporting her income, that is not the same as having a tax free income based on a treaty. Worldwide incomes are reported, the GC makes you a resident for tax purposes. If she is paying tax in the philippines on her earnings, your CSS would be wrong if you say it is untaxed. If the agreement allows her earning to be tax free in the US because she pays tax in the Philippines, it will be in her tax documents.
You say she has a green card but then you said in another post that she is a nonresident alien. A green card holder is a resident alien. Which is she? DOES she actually have a green card? If so, she is a RESIDENT alien.
@patsmom Sorry, I just jumbled up my words there. I meant to say she was a resident alien.
In any case, I know what I will be doing now so thank you for all the help everyone.