Q. Will I still have to pay PA state taxes?
A. Yes. If you work outside the state as a job requirement, you are only subject to PA State income tax on the days you work in PA. But if you work outside PA for your own convenience, you are subject to PA State income tax on all your income. New York, Nebraska, Delaware and New Jersey have the same rule. Your emloyer will probably continue to withhold PA tax.
References:
https://www.revenue.pa.gov/FormsandPublications/PAPersonalIncomeTaxGuide/Pages/Gross-Compensation.as...
http://www.journalofaccountancy.com/issues/2009/jun/20091371.html
Q. What about local taxes in Pittsburgh and Seattle?
A. Probably. You may have to do some more research. Again, you employer will probably withhold Pittsburg tax. Your resident city will usually give you a credit or partial credit, for tax paid to the work location city; but I'm not familiar with Seattle.
