I'm already in the independent contractor boat. So my next steps are to learn how to pay quarterly IRS payments (fun). Should I just follow the form or do I need to use a software tool to better calculate this stuff? My case is pretty simple, I'm a software developer making a typical amount, working 40 hours a week. My expenses are pretty common (just a laptop and probably nothing else) and not too frequent so whatever solution I use should account for calculating and listing those.
The worksheet in Form 1040-ES walks you through the process beginning to end. It's comprised of 2 worksheets which total 30 lines and result with the sum you should pay.
In effect, you are asked to guess your full year earnings and perform some calculations as though you were filing a full tax return. If your first estimate is correct, you'll have level payments through the year. If your actual income varies, you may send in too much or too little for each quarter, and will adjust as you go. With a 4th quarter payment not due until January 15th, you get one last chance to make sure your payments are enough to avoid a penalty.