Greetings! This is your friendly reminder that your 3rd quarter 2017 Form 1040-ES estimated tax payment is due Friday September 15, 2017. Be sure your payment is postmarked on or before that date. I recommend you mail it via certified mail (minimum) with return receipt requested (preferable) to prove it was mailed timely. Enclose your voucher and check loose in an envelope (do not staple or otherwise attach). Also, make the check payable to “U.S. Treasury” and put the taxpayer’s social security number (leaving off two digits: 123-45-XX89), phone number, and the words “3rd quarter 2017 Form 1040-ES” on the check.