The online help that should be improved is the following:
https://turbotax.intuit.com/tax-tips/state-taxes/multiple-states-where-to-file/L5NxnNH21
The underlined portion should be reworded as it could imply that employee wages from a company located in another state would be taxable, but that is not true unless the services were performed in that state (at least for California). The source rule for California is complex in that for employee wages it is where the services are performed (NOT where the business paying wages is located nor where the paycheck comes from) while for contractor (i.e. Schedule C) business income it is where the purchaser of the service receives the benefit that matters (so sales or support to a customer in California would be taxable).
You are a Nonresident of a state if you did not live in that state at any time during the tax year, but you did receive income from that state because you:
- Worked in the state (but did not live there)
- Received income from sources (rental property, business, etc.) within the state, or
- Received income as a beneficiary of an estate or trust from sources within the state
