I'm back to say how this played out.
In September, I got two notices from the IRS:
- A notice, as expected, that I had overpaid my taxes and they were issuing a refund
- A notice, unexpected, that I had underpaid my taxes and I owed them money
Thankfully, the former was for a greater sum than the latter. I deposited their check, wrote them a check for what they said I owed, and called it good. I did not receive an individualized letter or any kind of prose explanation of the situation. I do not know why there were two adjustments.
It's been several weeks since there has been any activity, so I believe this is finally settled. Thanks for the help @macuser_22 and everyone else in this thread.
