"The state of Delaware doesn't tax franchise fees, intellectual property payments and other 'passive' income. As a result, thousands of companies with operations in higher-tax states (in the past including energy companies like Shell and Enron, and telecom companies like Comcast and News Corp.) set up Delaware subsidiaries to collect fees from their out-of-state subsidiaries, rendering them effectively state-income-tax-free.
New Jersey, Ohio and other states have changed their laws to make it tougher to claim a Delaware exemption. But Pennsylvania Republicans turned back efforts by former Gov. Ed Rendell and his Democratic allies to do the same.
... the Reed-Depasquale Bill's "add-on" requirements would enable the state Revenue Department to collect from companies that attempted to use the Delaware loophole, without burdening other businesses."