You shoulda made 4 quarterly estimated payments, during the year.

You are now expected to pay the full balance due before April 15, 2018. However the IRS will let you apply for an installment agreement. Installment payments are almost always approved. There is an IRS fee for this in addition to interest. The choice will come up during the filing section of the TurboTax program.

The TT program will also include a section for preparing your 2018 quarterly payment vouchers.

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In order to sign up for a payment plan, you need to go to the File section of TurboTax, then when you get to the screen "<your name>, just one more step and we'll file your returns" select the Revisit link under "Here's how you chose to pay your taxes". Then on the screen "How would you like to pay your federal taxes?" you should see the last option listed as "I want to request an installment plan". 

. In addition to the interest, there is a fee of $225 ($43 if you meet poverty guidelines). The fee drops to $107 if you agree to direct bank debit.

The Turbotax help topic at this link explains how to set up a plan:

http://turbotax.intuit.com/support/kb/general-program-issues/tax-essentials/6391.html

Also see

http://www.irs.gov/pub/irs-pdf/f9465.pdf form

https://www.irs.gov/pub/irs-pdf/i9465.pdf  instructions.

To request an installment plan Fill out form 9465 to request the installment plan, and mail it in. It can also be submitted on line at www.irs.gov