Unfortunately, the form won't let you leave values blank -- unless you leave the entire row blank.
On my form, only column A has values, column B and C are blank. Leaving these blank in Turbotax and trying to submit generates red error text under each of the boxes I left blank.
I did find a solution though. You can find out the Row B value at https://www.healthcare.gov/tax-tool/#/. If you're in a state or locale (like DC) that has it own program, you can google something like "slcsp lookup tool" and your state. I guess most don't get the monthly advance payment for Row C, so I entered 0 for that column.
This is a fix that Turbotax needs to address given that there is no way to submit the form with blank values.
