If you have PhD training-related fellowship income (postbac, grad student, postdoc, etc.), your income tax is almost certainly not being automatically withheld, and you must grapple with the estimated tax system.
You need to 1) manually figure out if you owe estimated tax and in what amount and 2) make the payments if required.
This process can be a daunting to tackle for the first time, and there isn't an easy software product to help you with it. Don't let uncertainties about the process prevent you from paying your tax due (you may be fined) or, worse, distract you from your research!
I have removed all the stress from the process of paying quarterly estimated tax through my workshop, which is designed specifically for domestic US fellowship recipients. When you buy the workshop, you will maintain access for one full year, including updates if the calendar year changes.
The self-paced video workshop walks you line by line through filling out the necessary form to calculate your quarterly estimated tax, including discussions of many common special scenarios PhD trainees experience, such as switching onto a fellowship mid-year, having no tax liability in 2017, and filing a joint tax return with your spouse. I also include an Excel spreadsheet to help you with the math in the form.
Best of all, I will hold one live Q&A session leading up to each estimated tax deadline (four in your supported year of the workshop) to clear up any questions that arise for you during the recorded portion of the workshop. It's no problem if you can't attend live; you may submit questions in advance and will receive a recording of the session.
Purchase the workshop today to have the smoothest possible experience of calculating and paying quarterly estimated tax on your PhD fellowship!