I had a lovely client who had to file a US tax return and after much going back and forth finding numbers from eons ago when she lived in the US, we filed her US tax return and I also filled out Form 2848 - Power of Attorney as a safety measure. The IRS responded and said that the client's Social Security Number was not valid.
I had the client call Montana which is the Social Security office for Alberta Residents. By the way, this office has been quite helpful dealing with the clients I have directed to this phone number. A few clients have driven down there and, it seems, that they are treated very well on physical visits as well. You don't often see this with the US government so it's nice to know it exists. Mostly, I have just sent clients needing social security numbers so they can file Head of Household which offers better tax rates and also higher thresholds for taxes such as the Net Investment Income Tax. Anyhow, this elderly client contacted the Montana Social Security Office and asked her a bunch of questions. Her Social Security Number was indeed valid and the Social Security asked about her husband. He had died and they were divorced and his next wife was only a short term marriage.
The Montana Social Security person scheduled another phone call with the client a few weeks later and they called and asked the client more questions. Turns out she does qualify for her deceased first husband's social security - they were married for quite some time. This is great news, the client is elderly and does live in the US for part of the year and with the social security she also qualifies for health insurance in the US which is great because her health is deteriorating and I am sure the premiums for travel insurance while in the US is not easy.
Average social security benefits are $1,404 USD per month or $16,848 USD per year - it could be as high as $2,788 USD per month or $33,456 USD per year. This is a nice surprise!