When you send a check to the IRS, you need to list your Social Security Number and tell the IRS what year the payment is for. Otherwise, they won't know how to credit your money.
If you have a record of the canceled check, or a receipt for the money order, you can send a copy of that with a voucher for the payment you already made.
You can download Form 1040-ES free from
the IRS. Make sure you download the correct year for the forms you want to submit. The correct address to use depends upon your state and is listed in the instructions.
TurboTax will also create Form 1040-ES if you file with self-employment income. If you file your 2016 return with us, the 1040-ES forms will be for 2017.
