Edited [03/24/2021 @ 10:49 AM PDT]
Unless the work you do can only be done in CO or your home office meets the test of being a "bona fide employer office", then you are subject to NY tax on your earnings. (It does not make any difference if you have ever set foot in NY).
New York is a "convenience of the employer" state, which means they treat your teleworking income as "NY-sourced" income - just as if you were working in NY. Put another way, if you are working in CO for the convenience of your NY employer, then your earnings are subject to NY tax.
There are exceptions to this rule - if your home office is considered a "bona fide employer office" and is located outside NYS, then your earnings are NOT considered as NY-source income.
See pages 3-5 of New York Tax Treatment of Nonresidents and Part-Year Residents Application of the Convenience of the... for "Factors to apply to determine if a home office is a bona fide employer office".
Absent an exception:
Because you are a CO resident, your NY earnings are also subject to CO tax.
You will have to file a NY non-resident tax return and pay NY tax on the earnings from your NY employer.
You will also file a CO resident tax return, paying tax on all your earnings (including those from NY). CO will give you a credit (against CO tax) for any NY tax paid on the NY income - this is how states avoid "double-taxation".
To make this work correctly in TurboTax, you have to prepare the NY (non-resident return) first; that way the program knows haw much of a tax credit you will get from CO.
@Opus17 @TomD8
