To determine if you meet the substantial presence test for 2020, count the full 120 days of presence in 2020, 40 days in 2019 (1/3 of 120), and 20 days in 2018 (1/6 of 120). Since the total for the 3-year period is 180 days, you are not considered a resident under the substantial presence test: for 2020.

How do I know if I pass the substantial presence test?

If your "Total Days of Presence" is 183 or greater, then you pass the Substantial Presence Test and are a resident alien for tax purposes.

What is a pass a substantial presence test?

You pass the substantial presence test if you were “physically present in the United States on at least”: 31 days of the current year. 183 days during the past three years.