I have seen many posts about market based sourcing of income and I wanted to add a couple of items. California has had a market based sourcing of income since at least 2014. This is not a new thing (they have made some recent amendments). Business income has never been sourced based off of where the owner lives. Service income has historically been sourced based on where the services has been performed. With the advent of the internet there was a split between where the service has been performed and where the customer gets the benefit of the service. Many states have adopted a market based approach since then.
All that being said CA could be wrong in their assessment. You should make sure that the amount is correct.
