If you sell at a loss, you do not even need to report it on your tax return, unless you got a tax document, usually a 1099-S. The 1099-S may have been included in your closing documents, instead of arriving in the mail, in Jan. or Feb. of the following year.
If you get a 1099-S, you report the sale on form 8949 and schedule D and show an adjustment for the loss on form 8949 in column (g) so that you report $0 as your gain/loss. TurboTax does this automatically if you identify the sale as a second home or personal use property.
