Let's say you live in FL, but take a one month vacation in NY. Are you obligated to pay NY state income tax on the money you make trading from there for that month? Does this count as NY source income even though your physical location really wasn't important when it comes to making money. You're just on a workcation.
https://www.tax.ny.gov/pubs_and_bulls/tg_bulletins/pit/ny_source_income_nonresident.htm Non-residents can still be required to pay NY state taxes. It's about source income. I'm not sure if this qualifies as source income though.
In that case, go right ahead and pay the extra tax. Uncle Sam will be happy. But think about this for a minute...how is the IRS going to know you were in NY for a month? They won't.
Pretty easy from your bank account. I'm actually thinking of going there for 4 months during the summer (June through September when the weather here sucks). That would be even more obvious.
You are confusing this really bad. You are a FL resident and therefore pay income taxes as a FL resident. If you are in NY for a month and trade there while on vacation that is not establishing any residency in NY. States only taxes income of residents or people who have business operations within their state on a regular recurring basis.
I worked for a finance industry company with a New York headquarters outside of New York. Every year, employees were required to certify they were not New York State residents and expected to be working in New York for 14 or fewer days to avoid New York income tax withholding. But I suppose if your income is from trading and you vacation there, New York State won't know about it unless you tell them.
For example if you are a NJ resident but have your LLC offices in New York. Even though the LLC is a pass through and you pay income taxes in NJ, you still file a return in NY and maybe pay a state tax/fee for operating business in NY. Trading for a month in another state is nothing like that. it is like saying you run and own a company in FL and spent 4 days in NY for meetings and still ran the business, do you owe NY income tax? Uh....no.
Even then there is no NEXUS with NY. a NEXUS is required for taxes to be considered. The employees you mention were being asked to prove there was no NY nexus in the operations of the company. By the way, can you explain a NY HQ outside of NY??