After the initial legislation expired after 1999, the PTC was allowed to lapse for a year, as it was again after 2001 and 2003. As the wind industry lobby has noted, wind development dropped precipitously in years when the PTC was not available to help energy companies avoid taxes.<ref>American Wind Energy Association. 2015. “Wind Energy and the PTC”.</ref><ref>https://docs.wind-watch.org/schleede-big-money.pdf</ref>
In 2015, legislation ended the PTC for non-wind renewables after 2016 and established a phase-out for wind. Facilities first claiming the PTC in 2017 will get 80% of its value, in 2018 60%, and in 2019 40%. After 2019, new facilities could not claim the PTC.
In late 2019 , the PTC (and ITC – see below) was extended for 1 year at the 2018 rate.<ref>https://www.irs.gov/instructions/i8835</ref>
The PTC can be claimed for the year in which construction began if continuous progress is made towards completion for up to 4 years. For example, if a project commences construction in 2019, the developer can claim the 2019 PTC if the facility is operational before the end of 2023 and then take advantage of the tax credit until 2033.