We ended up leaving it blank. I did a fake return where I did an itemized deduction and did end up getting some refund even with that box 2 blank, but only because I was Itemizing. I believe because of the new tax structure, and how little interest we paid half-way through the year, the Standard Deduction still was a better savings in the end. This does go along with the Official Turbo Tax answer below
Do let me know if you hear anything differently, I haven't efiled yet.
