Well, my income was never 'Massachusetts sourced'. I work for a large Canadian company with offices in almost all US states. Office location assignment is what dictates what taxes are withheld, but there is a way to manually adjust on the back-end to change the withholdings based on residence, which I have done.
Massachusetts would prefer to withhold tax from 100 per cent of my income, but as my presence in the state is inconsistent and not predictable, I chose to post-pay income taxes based on what is actually owed. Because of the way we bill our time in the professional services industry, the (physical) work location is recorded as well, so I have accurate records to this effect.
Income taxes are levied from an objective standpoint, in most cases this is established by physical presence in a jurisdiction. The reasons why an employee is working in a particular place versus another is irrelevant. The taxes are owed because the labour was performed there.
