Scroll down to Instructions for Form IT-203-B, Nonresident and Part-Year Resident Income Allocation and College Tuition Itemized Deduction Worksheet in this NY tax reference. The instructions for Line 1 explain how New York wants you to do the allocation:
https://www.tax.ny.gov/forms/html-instructions/2023/it/it203i-2023.htm#it203bi
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
