We have seen many articles on this COVID-19 question about US tax residency and what happens if you stay more than 121 days in the US during 2020, the IRS finally came out with an answer today: the days a ‘trapped’ individual stays in the US will not count toward the substantial presence test –so normally someone can stay 121 days per year & with the IRS’ latest guidance they can stay an extra 60 days.

https://www.irs.gov/pub/irs-drop/rp-20-20.pdf