Green Card and Social Security

Yes.

Taxability may be affected by the tax treaty (if any) between the U.S. and the former resident alien's country of citizenship.

The answer may vary depending on what country he's from. There are some countries with tax treaties with the U.S. which permit credit toward their native SS system instead of the U.S.'s....

A correction... that isn't a tax treaty but a social security treaty.

If there is a relevant treaty, then it is a tax treaty.

If the question was about taxes and taxability, I would agree but it was not. It was on whether they could receive social security. If you search for the treaty using the term Tax Treaty, you will not find it. If you search using the term Social Security Treaty, you will.

For Australia, it's definently a TAX treaty.

The Social Security Administration addresses your question in glorious detail in SSA Publication No. 05-10137, June 2009. This pub explains who will or won't receive benefits if one resides outside the U.S.A.

I looked at the Australia-US Tax Treaty. Article 18 is the only one which deals with Social Security and only talks about if it is paid, not what and how much benefit is received.

Whereas, the Australia-US Social Security Agreement deals with those who have worked in one country and now live in the other, what and how much benefit they receive from that work. See

However, it's still in a TAX treaty.... That was my sole point.