Thanks again for the quick response. I think I am misunderstanding something. Based on lines 31 through 36 on the below linked 2019 NYS tax form, it seems to me NYS taxable income is based on federal income, not income earned in NYS. That income is also used to determine your tax rate and tax due on line 38.
Only after determining the base tax (line 44), which includes non-NYS income, is there a proration. However, it still results in me owning more NYS tax (at least according to NYS) when including NJ only income. Which feels wrong. But maybe I am isunderstanding?
https://www.tax.ny.gov/pdf/2019/inc/it203_2019_fill_in.pdf
2019 NYS Non-Resident Tax Form
