There are various apps on the web that you can use to estimate your self-employment payments due. TurboTax had one, but I see it is not active any more.
The advise I give anyone starting out working on their own is to purchase Intuit QuickBooks and TurboTax Bundle. Once you set up QuickBooks, it takes information from your financial accounts and does all the calculations for you.
It will tell you when your estimated payment is due and how much to send. You will get a voucher to mail with your check or directions to send it online. Each quarter it makes adjustments so that you are not under or overpaying.
You enter your expenses in categories and mark the ones you need for taxes. When it is time to file you taxes it pulls the information from the previous year into the correct places in TurboTax. Preparing your self-employment tax return is as simple as pushing the button to bring the information from QuickBooks to TurboTax Self Employed.
You, of course, can decide to do your bookkeeping in whatever way is best for you.
Self-Employed Individuals Tax Center | Internal Revenue Service (irs.gov)
