A timeshare or vacation home is considered a personal capital asset and the sale is reported on Schedule D Capital Gains or Losses. A gain on such a sale is reportable income. If you incurred a loss on the sale, the IRS doesn't allow you to deduct the loss. Knowing what I know about timeshares, I am assuming it will be a loss though I am hoping that it is a gain. If you have had the timeshare for more then a year then it would be a long-term capital gain. If less then a year then it would be a short-term capital gain.
We have owned it for over 15 years (if not more) so what difference would that make to how much we would owe? It will likely be a loss of income upon the sale.