The IRS will let you pay off your federal tax debt in monthly payments through an installment agreement.
If you haven't filed yet, go to the File section of TurboTax, and on the How do you want to pay your federal taxes? screen, select Request an IRS payment plan.
If you already filed, or you can't find this option in TurboTax, you can apply for a payment plan (Form 9465) at the IRS Payment Plans and Installment Agreements website. Make sure you've filed your return before applying through their site.
Most states offer an installment payment plan as well, although the procedure varies from state to state. You can contact your state Department of Revenue for details.