I've been doing estimated taxes for the past decade or so. A real PITA compared to our wage slave friends. I decided early on that, instead of going through their complicated calculations each quarter, I would just take last year's tax % off the top line of my earnings and send it to them. This saved me a lot of time and agony. It worked just fine for all but two years. One where I got a big check in the 4tyh quarter and ended up paying a penalty. One where a deal fell through and I got a big refund.

Those of you who earn a salary and only have to do your taxes once a year do not realize how easy you have it. But those of us who are self employed can get the waters to ourselves on Wednesdays.