I left the USA in Feb 2020 (I was a resident alien in 2019). To which year's tax return should I attach the early residency termination statement, 2019 or 2020?

[daliachicago]

I have a closer connection (work) to another country and I will not satisfy the substantial presence test during 2020.

[RobertG]

Attach it to 2020.

The residency termination date for an alien who meets the green card test is the first day during the calendar year that the alien is no longer a lawful permanent resident if the individual establishes that, for the remainder of the calendar year, his or her tax home was in a foreign country and he or she maintained a closer connection to that foreign country than to the United States.

26 C.F.R. § 301.7701(b)-4(b)(2)