What puzzles me is the size of the Premium Tax Credit (PTC) that got repaid. I am having trouble understanding how she got that much in the first place.

Did she report a very low estimated income to the federal marketplace at the beginning of 2017? Did she have significant change events in 2017 (like getting married to you or making far more money that she expected) that she did not report to the marketplace in mid-year?

$19k is very expensive but not totally unbelievable, particularly for a nice (gold) policy. 

No. she make what she estimated.  She only works part time and only earns $7000.  We did take a draw from our investments that put us over, but repaying 15k?  doesn't seem right.

Well, let's check some things.

1. Was the number on line 46 on the 1040 actually $14,496?

2. What are lines 24 and 25 on form 8962?

3. What is your filing status?

4. What is your entry on line 5 on the 8962?

5. Did she elect to take the Health Care Tax Credit (HCTC)?

6. Was she not legally in the US? (seems like a strange question to ask, but it affects the limit of PTC you have to repay).

7. What are lines 27, 28, and 29 on the 8962?