calculator for estimated tax payments - Aaron Graves, PhDude Replica

Estimated Tax Payment Calculator

Use this quick tool to estimate your federal quarterly payments. It includes income tax, self-employment tax, withholding, credits, and a safe-harbor comparison.

Filing Status

Expected Net Self-Employment Income ($)

If you are not self-employed, leave this at 0.

Other Expected Taxable Income ($)

Above-the-Line Deductions ($)

Examples: HSA contributions, deductible IRA, student loan interest.

Standard or Itemized Deduction ($)

Auto-filled with a standard deduction estimate when filing status changes.

Expected Tax Credits ($)

Expected Federal Withholding for the Year ($)

Prior-Year Total Tax ($, optional safe harbor)

Prior-Year AGI ($, optional; used for 110% rule)

What estimated tax payments are

Estimated tax payments are periodic prepayments you send to the IRS when taxes are not automatically withheld from your income. This applies to many freelancers, consultants, small business owners, investors, and retirees with non-wage income.

Instead of paying everything next April, the system is “pay as you go.” In practice, that usually means four quarterly payments. Paying enough during the year helps you avoid underpayment penalties and keeps your cash flow predictable.

Who should use this calculator

Self-employed people with 1099 income
Side-hustlers with growing freelance revenue
Taxpayers with rental, investment, or pass-through income
Anyone whose withholding is too low to cover annual tax

How this calculator works

1) Estimate annual tax

The calculator adds expected income, subtracts deductions, and applies progressive federal tax brackets. If you include self-employment income, it also estimates self-employment tax and the related half-SE-tax deduction.

2) Compare safe-harbor targets

The tool compares two common targets:

90% of current-year tax
100% of prior-year tax (or 110% if prior-year AGI is above $150,000)

It then uses the lower of those two amounts as your annual payment goal (when prior-year tax is provided).

3) Subtract withholding and split into quarters

Any expected W-2 withholding is subtracted from the annual target, and the remaining amount is divided into four equal estimated payments.

Quarterly due dates (typical schedule)

Q1: April 15
Q2: June 15
Q3: September 15
Q4: January 15 (next year)

Tips for more accurate estimates

Recalculate each quarter as income changes.
Be conservative with deductions until records are finalized.
Track withholding from payroll if you also have a W-2 job.
Build a separate “tax savings” account so quarterly payments are ready.
Use your accountant’s projections for final numbers when possible.

Important note

This is an educational planning tool, not legal or tax advice. Federal and state rules change over time, and your exact tax situation may involve additional items (AMT, capital gains rates, additional Medicare tax, QBI deduction, credits phaseouts, and more). Use this calculator as a starting point and confirm final payment amounts with a tax professional.