How can a permanent resident collect SSI if he or she does not have 40 quarters of coverage on their own?

Sometimes it takes a question before I understand the answer.  I recently was asked about whether or not a permanent resident could collect SSI when the permanent residence was obtained through marriage.   The general rule is that a permanent resident (who entered after 1996) may only collect SSI if 1) he or she waits five years after  entry before applying and 2) is credited with 40 quarters of work.  (There are other rules for permanent residents who have obtained status through a humanitarian immigration option such as asylum.)
I always thought that permanent residents (through marriage) would not have 40 quarters of work (approximately 10 years of work history) because they would have only received work authorization upon applying for permanent residence.  At the most, they would only have a few years of work history.  However, in looking at the question further,  I realized that a permanent resident may be credited with a spouse’s earned income.  For example, if the US citizen has been working, then the lawful permanent spouse may use her citizen’s husband’s earned quarters of coverage to reach the 40 quarters.  The only exception to this is that the citizen spouse’s quarters of coverage cannot be credited if he himself has been receiving a means tested public benefit.  This is unlikely to happen because a person is unlikely to receive a means tested benefit if he is working.
There is therefore a way for a permanent resident to obtain SSI after five years as long as her spouse has sufficient quarters of coverage that can be credited to her.  There are also ways to obtain credits of coverage through a parent.  You can read more about this in Social Security’s Program Operations Manual System (POMS).
Of course another option is that the permanent resident may apply for citizenship.  When married to US citizens, permanent residents may apply for citizenship as early as 2 years and 9 months from the date they obtained their green cards.  Upon receipt of citizenship, the 40 quarter rule does not apply.