@Hal_Al - there are plenty of comments and question on these boards about the NY situation. From what I understand if your NY employer permits you to work out of state for your personal convenience, the income is taxable to NY, even though you may have not ever been in NY. And that is why payroll departments withhold NY income tax. The tax does apply.
That would be a different situation than a NY based company that hired someone in another state for the sole purpose of working from that other state. Or a NY based employee who the firm transferred to another state. In these instances, the employee is NOT working from the other state for personal convenience.
one such article on this topic and the challenges:
https://news.bloombergtax.com/tax-insights-and-commentary/new-yorks-convenience-of-employer-test-sta...
it is unusual.
