How can I print Form 1040-ES for payments in 2018? I did not owe any taxes for 2017 so the forms were not included in my paperwork, but I need to pre-pay taxes for 2018.

So you have already filed your 2017 return?

CAUTION:
I can tell you how to open up your already-filed 2017 return to go through the W4 and estimated taxes interview.  It's OK to use that section, but do not go back into other areas of your return to change things or experiment, since any changes would be saved and mess up your return.

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You can go through the section "W-4 and Estimated Taxes" to figure your customized 1040-ES quarterly tax payments.    There is also a place in that interview to enter what you have already paid for 2018 (if applicable), and it will let you include any expected income changes or any other changes you have for 2018.

• Log in and go to "Your Tax Returns & Documents".  Click on that line or the word SHOW to expand, then choose 2017.
  
• Since you have already filed, you'll need to open your return back up.
• Choose "Add a State."  (you don't really add one; that's just to get the return to open back up.)
  
• Once the return is open and past the blue-green screen, click in the left menu column on Federal.
  
• Then at the top choose subtab "Other Tax Situations"
• Scroll way down to last category "Other Tax Forms"
• Find topic "Form W-4 and Estimated Taxes" and click Start or Update.
• If you need to adjust withholding, go through the W-4 interview.
  
• If you don't need the W-4 (withholding) interview, you can skip that part and go to the 2018 estimated taxes interview.
• You may get a screen that says "Review your Estimates for 2018?" and asks "Do you want to adjust/review your income or deductions".  Say YES (or Review Now), so you can get to the additional questions.
• You will go through a lot of screens asking about expected income and deductions.
• Finally, you will come to a screen that says "Enter Payments You Expect to Make."
• There are some boxes there that say "Enter estimated tax payments you've already made for 2018."  
• Next screen will ask "which method" to use to calculate your 2018 estimated payments.
• Next screen will ask if you want to print vouchers.

If you don't want to mail paperwork each quarter, you can pay at the IRS website using IRS Direct Pay out of your bank account.   There is no fee to pay out of your bank account.     There IS a fee, however, if you pay by debit or credit card.   If you pay there, be sure to indicate the correct tax year, and to print out the confirmation page for your records.

<a rel="nofollow" target="_blank" href="https://www.irs.gov/payments/direct-pay">https://www.irs.gov/payments/direct-pay</a>

Or you can set up an account at EFTPS and pay quarterly out of your bank account with no fee.

The Treasury offers the free EFTPS (Electronic Federal Tax Payment System).  You can make 1040-ES payments electronically, as well as other Federal tax payments including balances due on your annual Form 1040, etc.   You have to set it up in advance with your banking info at the website.  Once you enroll and they verify your info, the Treasury will send you a PIN in the mail, which you use each time you make a payment.  The payment is then debited from your bank account.    You can set up multiple payments in advance, or even make extra payments.  Once you set it up, you can even make tax payments by phone, and you don't have to mail in any paper 1040-ES forms.  You can print out confirmations or download the confirmation as a PDF.   Read more at the sites below.

There is an extensive FAQ at:  <a rel="nofollow" target="_blank" href="https://www.eftps.gov/">https://www.eftps.gov/</a>

Also see this article:
<a rel="nofollow" target="_blank" href="http://www.irs.gov/uac/EFTPS-The-Electronic-Federal-Tax-Payment-System">http://www.irs.gov/uac/EFTPS-The-Electronic-Federal-Tax-Payment-System</a>