The pandemic had resulted in travel restrictions. As a result lot of aliens, including, snowbirds got stranded in the United States. The Internal Revenue Service issued relief for such aliens by issuing Revenue Procedure 2020-20. Revenue Procedure (RP) 2020-20 provides relief for the eligible individuals who did not anticipate to meet the substantial presence test.
RP 2020-20 simply treats Covid-19 related travel disruptions as a medical emergency. Under the relief, an eligible individual can exclude a "single" period of up to 60 consecutive days. Such a period must start on or after February 01, 2020, and on or before April 1, 2020.
An individual can claim this exception by filing Form 8843, i.e. Statement for Exempt Individuals and Individuals with Medical Condition.
Candian snowbirds are generally not required to file form 8833, they need to file form 8840.