U.S. Internal Revenue Service · reviewed 2026-10-09
What this source supports: The IRS explains when individuals and sole proprietors must pay estimated tax quarterly and how safe-harbor payments work.
Source limit: Safe-harbor percentages depend on prior-year adjusted gross income. Confirm with the current-year instructions.
These sources support the statements above. They do not show that every person needs this guide. They do not show a specific result.
Limits
This guide sets a savings target from your numbers. It does not prepare returns, compute exact liabilities, or give tax advice.
Safe-harbor percentages depend on prior-year adjusted gross income. Confirm with the current-year instructions.
Use current instructions from the responsible organization. This guide is a planning aid, not an official decision or a substitute for qualified advice.
Common questions
What does the App compute?
Turn quarterly net profit and a chosen rate into the dollar amount you move to the tax bucket.
What does the App not do?
This App multiplies numbers you enter. It does not compute your actual tax, file returns, or replace a tax professional.
Where do the numbers come from?
You enter every number yourself. The sources support the method and the limits. They do not produce a result for your specific case. Keep the original documents next to the sheet you build.
Before you start
Open the linked source page and keep it beside you.
Gather the values the App asks for:
Quarterly net profit in dollars.
Set-aside rate in percent.
Set aside ten quiet minutes; rushed numbers are the main error this guide prevents.
Free Companion App
The App computes the worked example with your own numbers, in your browser.
APP 1
Estimated Tax Set-Aside Planner
Turn quarterly net profit and a chosen rate into the dollar amount you move to the tax bucket.
This guide is edited for clarity and checked against the sources it links. It is not a substitute for official instructions or qualified advice. A linked source does not show that every person needs this guide.