See the back of the 1099-S form.
Box 6. Shows certain real estate tax on a residence charged to the buyer at settlement. If you have already paid the real estate tax for the period that includes the sale date, subtract the amount in box 6 from the amount already paid to determine your deductible real estate tax. But if you have already deducted the real estate tax in a prior year, generally report this amount as income on the “Other income” line of Schedule 1 (Form 1040). For more information, see Pub. 523, Pub. 525, and Pub. 530.
1099-S, box 6, "buyers part of real estate tax" does not refer to the sale. It is the real estate tax is paid for owning the home and is entered on Schedule A, where appropriate.
