@Jon wrote:
Thank you for this in-depth answer sorting the aspects of QC and QR. I am pleased to provide a happy update, I talked it over with him explaining why she wouldn't be claimable, and he did not know about the income threshold of $4300. He won't be looking to claim her as a dependent, so all is sorted.
Thank you both, Bsch4477 and Hal_Al for the great answers.
Just to clarify for all:
1. If your wife decides to file a joint return with you, that immediately preludes anyone from claiming her as a dependent**, even if she otherwise qualifies.
a. **Unless the only reason she files a joint tax return is to claim a refund of withholding, and neither she nor her spouses owes any tax or claims any credits or deductions. (This would be an unusual and rare situation but I need to point it out or someone will nitpick me.)
2. Your wife does not qualify to be claimed as a dependent in any case, based on her age, lack of student status, and income.
Note that, even if your father-in-law had not acquiesced, you would have been able to file MFJ and claim the AOTC and anything else. Your wife's decision to file a joint return overrides everything else. You might have been blocked from e-filing, depending on who filed first, but you could mail your return and claim all the credits you are entitled to. The IRS would eventually have recalculated your father-in-law's tax return and sent him a bill.
