BBCW, for non-US citizens, over what length of must one have worked in the US to qualify for social security benefits?
To qualify for U.S. Social Security retirement benefits (and for spousal retirement benefits)(**) there are two ways:
(a) Non-trivial(*) contributions to the U.S. Social Security system within any 10 calendar years. They do not have to be consecutive years, and they do not have to be entire years. Indeed, as few as 10 paychecks could be enough to get the job done.(***)
(b) Alternatively, non-trivial(*) contributions to the U.S. Social Security system within any 2 calendar years, provided you have also made contributions into the social insurance systems of any treaty country(ies) within any 8 other years. As few as 2 U.S. paychecks could be enough to qualify using the treaty "totalization" method.
The
amount of the retirement benefit (and associated spousal benefit) is based on lifetime earnings, and with a rather complex formula. The retirement benefit amount probably won't be very much if you just barely clear the hurdle to qualify for some level of benefits, but a few dollars is better than zero, of course.
(*) "Non-trivial" in part (a) means 4 "quarters of coverage" (QoCs) per year. One QoC in the year 2018 is equal to gross earnings of US$1,320. So, in 2018, to get the maximum 4 QoCs you would need at least US$5,280 of gross earnings subject to U.S. payroll tax (Social Security contributions), and of course that payroll tax must be paid. If that happens in a single paycheck, that works. ("Quarter" isn't actually referring to any period of time.) You can only earn a maximum of 4 QoCs per calendar year.
"Non-trivial" in part (b) means 6 QoCs total. They can be split in any way, but since you can only earn a maximum of 4 per calendar year, you need at least 2 calendar years to get to 6.
The amount of earnings required to earn one QoC varies depending on the year since they are adjusted annually for inflation. U.S. Social Security publishes those figures
here.
(**) The legal spouses -- same or opposite sex, and in some cases ex-spouses -- of U.S. Social Security retirement benefit recipients are ordinarily eligible for spousal benefits, even if they never worked nor stepped foot in the United States. Spousal benefits are normally equal to one half of the retirement benefit, although spouses can only start receiving spousal benefits based on their own retirement age (minimum age 62 to start). If the primary retirement benefit recipient should predecease the spousal benefit recipient, then the spousal benefits end but the spouse picks up the retirement benefit amount for the rest of his/her life. The surviving spouse is also ordinarily able to receive a small death benefit, currently (2018) US$255. If the spouse qualifies for U.S. Social Security retirement benefits on his/her own merits then, if higher, that amount will prevail. Otherwise, the spousal benefit level will prevail.
(***) Qualifying for retirement benefits based on method (a) also qualifies the recipient for free U.S. Medicare Part A coverage. U.S. Medicare Part A is basic hospitalization coverage within the United States for those age 65 and older. Individuals who qualify for free U.S. Medicare Part A should notify the U.S. Social Security Administration about 3 months before their 65th birthday that they would like to start Part A coverage. Additional Medicare coverage is also available for purchase, but individuals who do not have the right to live in the United States should almost never add the paid Medicare coverage and should just accept the free Part A. For U.S. citizens living outside the United States at age 65+ this particular decision is a bit trickier.
