State tax filing

@Opus 17 

There's also this:

“A nonresident who works in another State but who performs no work in New York is not subject to New York State tax liability no matter for whose convenience or necessity he performs the work.” 

Hayes v. State Tax Comm, 61 A.D.2d 62, 64 (N.Y. App. Div. 1978)

Hayes v. State Tax Comm, 61 A.D.2d 62 | Casetext Search + Citator

And the definition of NY-source income of a non-resident from NY Tax Bulletin IT-615 refers only to income from work carried out in New York.

https://www.tax.ny.gov/pubs_and_bulls/tg_bulletins/pit/ny_source_income_nonresident.htm

I suspect the "convenience of the employer" rule was originally intended to prevent a non-resident who normally works in (and is taxed by) New York from deciding on his own to work from his out-of-state home and then claiming that that portion of his income isn't taxable by New York.  I doubt it was intended to tax non-residents who do not, and never did, work in New York.  My opinion, of course, is totally and 100% unofficial.