Sometimes employer's do a great job of that, but if you have any other form of income on which tax was not withheld, or your income has changed from last year, you may need to pay estimated tax. The program just doesn't know until you go through that part of the program and answer the questions.
You can click on the tab for Other Tax Situations at the top where it shows Federal Taxes, State taxes, etc.. Choose the Underpayment of estimated Taxes topic and complete the interview there. Doing so may end up with your not needing the form, but the program doesn't know until you answer the questions.