I live in WA, just north of the Columbia River border with OR... While there is no WA state income tax, there is an OR state income tax. Our office was in Portland, I travelled a good bit (usually to Utah/Wyoming) and earnings while not in Oregon was exempt from Oregon's grab. Sometimes Oregon would make you account for your time worked out of state and would prefer that your company report that information. Our company said, no - we aren't doing that.
One year after claiming I worked out of the state for some 200+ days, they wanted some actual evidence. Fortunately, Delta Airlines and Hilton had that information on-line which I sent to OR Revenue - and they accepted it.
Later I started working from home and they just accepted that without any real proof (though I am unsure what would have sufficed for that). Odd compliance and measurements going on in the bureaucracy, for sure!