Another question: I will be receiving a significant amount of income ($50k) on around May 17th. Any legal and ethnical way I can have this as WA source income and therefore not subject to CO state tax? The income is reimbursement for my house selling costs from my employer

This income will always be WA source income. That does not necessarily exempt it from CO taxation. Although I don't know CO tax law, I'm sure it is the same as any other state I *am* familiar with... namely, all income earned world-wide is taxable to CO if you are a resident of CO unless explicitly excluded by CO (or federal) tax law. So, the only way to avoid CO taxation on the $50K is to ensure that you receive it before you establish CO residency.

Ira