Notice 2016-31 updates prior guidance concerning the renewable electricity production tax credit (PTC) under section 45 and the energy investment tax credit (ITC) in lieu of the PTC under section 48. The notice reflects the extensions, under the Protecting Americans from Tax Hikes Act of 2015, of deadlines for beginning of construction for the PTC and ITC with respect to certain renewable energy facilities. In addition, the notice further extends and modifies the continuity safe harbor, provided in earlier guidance, and provides additional guidance regarding the application of the continuity safe harbor and the physical work test.