I suspect that there are many readers of this forum (probably the majority) who have spent at least some of their working life contributing to both the UK and US Social Security Systems.
Some, (myself included) only contributed for just a few years (less than 10) into the US system and spent most of their working career paying into the UK system. How many have disregarded their 'meagre' credits into the US system and then potentially walked away from what could be a nice little second pension?
I was well into my 50's and was on track to ensuring I would receive a full UK state pension (OAP) before I took another look at those US credits. Surprisingly I had accrued 36 credits but at that level would not be entitled to anything. I then started to look at what a pension would be worth if I could get to the magical 40 credits.
Armed with my full US earnings history and SS contributions (what an anorak!) I downloaded the US SS benefits calculator (found here:
https://www.ssa.gov/oact/anypia/anypia.html) and set about plugging in all the data.
To my absolute surprise, even after accounting for the dreaded WEP, I was still looking at a potential US SS pension of over $1,000 per month - plus a spousal pension at another 50%. Certainly not to be sniffed at!. Unlike the UK, the US system is earnings related.
So how could I get the additional credits I needed?
The last time I'd looked at the system (in the previous century!), the credits were referred to as quarters - because by working 4 quarters each year, you got the maximum 4 quarters as credits. Well the system changed some time ago and now it is simply credits instead of quarters - still only 4 credits maximum per year though. In 2022 you earn one credit for each $1,510 of earnings. So $6,040 of US SS eligible earnings in 2022 gets you the maximum 4 credits.
My initial concern that I'd need to work for a full year in the US to get over the threshold simply evaporated - all I needed to do was earn enough ($5,200 at the time for me) to get the 4 required credits.
I was fortunate enough to secure a 4 week consulting assignment in the US and earned the required amount - tbh though, I'd have taken a holiday to Florida and bagged groceries for as long as it took to get the 4 credits.
Roll on a few years and I'm now drawing both my UK & US pensions and with the current exchange rate my US SS pension (earned over 9 years and 1 month) is worth more than my UK state pension (the maximum - and earned over 35 years).
The moral of this story - Never EVER underestimate the real value of US Social Security Contributions - especially if you were a high earner - and if you're short a few credits, do the maths and allow yourself enough time to get over the threshold.