Work it out before you call anyone.

Four short questions and you have your estimated-payment schedule for the year, federal and California, with the safe-harbour figure worked out alongside it. Tick each payment off as you make it and the remaining quarters adjust.

Export the schedule as a PDF, or as a spreadsheet you can edit and import back if your numbers change mid-year. Due dates come out as calendar reminders. It runs entirely in your browser, so nothing you enter reaches us.

Sole proprietor, S corporation and C corporation side by side on your own numbers. It is built for California, so it prices the things that actually decide the answer here: the pass-through entity elective tax a sole proprietor is not allowed to elect, the §199A wage limit an owner salary unlocks, state disability insurance that no longer stops at a wage cap, and the 1.5% franchise tax with its $800 floor.

It also counts what a C corporation only defers rather than saves, and tells you when an election would cost you money instead of assuming it helps. Every rate is verified against irs.gov and ftb.ca.gov and cited on the page, and nothing you enter leaves your browser.