Quarterly estimated tax planner

How the quarterly estimated tax preview works

The preview runs the IRS 2026 Estimated Tax Worksheet from Form 1040-ES line by line on the numbers you enter^[f1040es]:

1. Self-employment tax. Net profit × 92.35%, then 2.9% Medicare plus 12.4% social security up to the wage base ($184,500 for 2026, minus your W-2 wages)^[ssa]. Half of it is deducted from income.
2. Income tax. Expected AGI minus the standard deduction (or your itemized total) and any QBI or Schedule 1-A deduction you enter, taxed with the 2026 Tax Rate Schedules printed in Form 1040-ES.
3. Other taxes. The 0.9% Additional Medicare Tax on wages and self-employment earnings above $200,000 ($250,000 joint, $125,000 separate).
4. Safe harbor. The required annual payment is the smaller of 90% of this year's tax or 100% of last year's tax, or 110% if last year's AGI was over $150,000 ($75,000 married filing separately)^[p505]. Withholding is subtracted, and no payments are required if the rest is zero or you would owe less than $1,000.
5. State. Your state's income tax is estimated with the same 2026 state engine that runs our state tax calculator, applied to your expected income, and spread over your state's own due dates.

Tax year 2027 uses the 2027 brackets and standard deduction from Rev. Proc. 2026-35^[rp2635] and the $192,300 wage base^[ssa27]. The IRS has not released the 2027 Form 1040-ES yet; we update the kit when it does.

Four worked examples, checked against the 1040-ES worksheet

Each example below was worked by hand through the worksheet lines and matches the preview to the cent (the full line-by-line worksheet is in the kit):

In the first case, 100% of 2025 tax ($8,000) is far below 90% of 2026 tax ($12,622.08), so after $7,000 of withholding only $1,000.00 has to go out in estimates. In the high-income case the 110% rule applies: 110% of $60,000 is $66,000.00, still less than 90% of 2026 tax, so $16,500.00 per quarter protects the household even though about $10,914.41 more is due in April. The California freelancer pays the state on its uneven 30/40/0/30 schedule^[ftb]; the Texas freelancer pays the IRS only. The self employment tax calculator shows the SE tax lines for $80,000.00 of profit ($11,303.64), and the quarterly tax calculator gives the federal amount alone.

State dates and thresholds in the planner

The planner knows the individual estimated tax dates, payment threshold and official form of every state the paycheck engine covers: most use the federal dates, California splits payments 30/40/0/30, Virginia starts on May 1, Delaware on April 30, Hawaii uses the 20th and Iowa the last day of the month, and Utah and Idaho do not require quarterly payments. The full table, with each state's form linked, is on the estimated tax due dates page.

What this kit is, and is not

The full kit costs $39/year, about $3.25/month. A missed or short payment is charged interest for each day it stays unpaid, at the IRS underpayment rate: 7% a year, compounded daily, for October to December 2026^[int]. On a $2,250 quarterly payment that is about $13 a month.

• It is self-service planning software. It calculates amounts and dates from the numbers you type and links to the official payment pages.
• It does not prepare or file a tax return, does not submit anything to the IRS or a state, and does not give tax advice for your situation.
• Everything you type stays in your browser. No e-mail address is collected on this page. E-mail reminders will be added when the reminder service opens; until then, the calendar file carries the reminders.

For a single paycheck question, the paycheck calculator shows how raising Form W-4 withholding could replace estimated payments.