That's the question: whether we are totally out of luck because, although we submitted the expenses to my spouse's plan when they were incurred in the 2nd half of 2020, they didn't actually deduct the remainder of the amounts from her pay until 2021.
It that's the case it answers my question.
However, it certainly would feel like we drew a short straw (to say it politely) as a result of her employer's weird plan year. (I.E. the funds were validly contributed to the plan on a pre-tax basis, and we actually had the corresponding expenses, but the plan wouldn't be serving its purpose if at the end of the day we don't get to use the funds as intended - to pay for dependent care on a pre-tax basis.) We would effectively have to line up deductions and expenses every half year (or other division if the fiscal year ended some date other than 6/30) not to have such a mismatch.
