United Technologies last week announced plans as part of its merger with Raytheon to relocate its headquarters to Boston from Farmington, Connecticut. CEO Greg Hayes says the move isn’t motivated by taxes. But as a new study documents, more businesses are leaving Connecticut as they get walloped with higher taxes that are bleeding the state.

Democrats in 2015 imposed a 20% surtax on top of the state’s 7.5% corporate rate, effectively raising the tax rate to 9%. They also increased the top income tax rate to 6.99% from 6.7%...