That's interesting. So if you don't take it in advance, they make you go through an additional step of looking up the SLCSP for yourself. And I imagine there's plenty of people that just don't complete the form and leave money on the table. And then how many people look it up wrong and the form calculates an incorrect amount. Then the IRS letters back and forth until the thing gets straightened out. That's what I call some real wisdom, right there!
The reason I'm interested is because this year I only have two months worth of APTC, so I didn't put in my estimated income; I'm just paying the two months worth. But I expect to get some PTC. As I mentioned, when I shop, I always record the SLCSP, but it often doesn't agree to the penny.