I got a tax bill for more than a hundred thousand dollars when I sold my primary residence a few years ago. No taxes were actually owed due to the primary resid

I got a tax bill for more than a hundred thousand dollars when I sold my primary residence a few years ago. No taxes were actually owed due to the primary residence carve out for capital gains. The sale had been reported to the IRS by a couple different entities (realtor and title company, IIRC) with a few dollar discrepancy, so the transaction was not merged, even though they for the same address (and single family home). I wrote the IRS a nice letter and they eventually replied that they were closing the case. Sometimes "unpaid" taxes are due to limitations of the IRS, which has historically had very legacy software (not sure if that has been fixed recently).