If you have enough federal taxes withheld from your pay or other sources of income, you don't need to pay quarterly estimated taxes. If you under withheld for 2018, TurboTax will create estimated payment vouchers for you. You are not required to use them. If you plan to increase your withholding for 2019 so that you are not under withheld at the end of the year, just destroy them if you don't need them.
