I began 2020 working abroad, but then began working (very) remotely from the US due to the pandemic. It was not until several months later that it became clear that I would not return abroad for the rest of the year. At that point my employer approved me to work abroad indefinitely, and switched me to being paid from a US subsidiary. They also backdated my salary to the start of when I originally returned to the US earlier in the year. They then paid my federal and state taxes for that entire time period.
The issue is that I moved from state A to state B about halfway through that time period, before they switched my payroll. So now I have a W2 from my employer showing that my salary for the whole year was taxed in the state B, and all state taxes were paid to state B. I now need to file part-year resident state returns for both states and I am wondering the correct way to compute my taxable income for the two states.
For example, suppose I got $100000 for the entire time period, but I lived in state A for 48% of the time and state B for 52% of the time. Can I report $48000 as taxable income for state A, and $52000 as taxable income for state B, even though this would conflict with the W2?
Or am I supposed to not consider any of the income to be taxable in state A? I have income in state A from other sources that will already be included on that return.