Fortunately, I had a really good person in the local? Social Security office handle my application. After our discussions, she gave me the option to undo/withdraw my SocSec application, so it had no impact on my 2020 HSA contributions. There's also the ability when you do start SocSec of getting back-payments for a few months.
Fortunately I'm still working, so don't need the SocSec funds. So I'm putting off applying for Social Security until July 2 (they have strange rules about the first day of the month). The six-month look-back will then go only to January, and I am therefore qualified to have contributed ALL of my HSA maximum for 2020.
In that July application, I'll be applying for Social Security retirement benefits to be active as of my 70th birthday in late March. Once my new application is approved, I'll be able to receive a check for all benefits from April forward that I "missed" because of my "late" application.
This solution won't work for everyone, but since I can continue working through July, it works for me.
