I'm using TurboTax 2018, so I assume that it should let me enter previous credits all the way up to 2017. The fact that it doesn't makes it look like something was missed during the annual update...
What I also don't understand is why it applies a lifetime cap of $200 for combined door and window purchases, when it seems that doors should not have such a cap, https://www.efile.com/tax-credit/energy-credit/.
