I would pay it directly to the tax collector's office. Next year's property taxes won't be billed and due until early next year, but the tax office has given me an estimate for next year's tax and said I could send them a check this year. My mortgage company collects escrow for taxes and will refund me any excess next year (after they see that the tax bill shows the tax has already been paid). The question is whether I could deduct the prepayment on this year's taxes.