Estimated Quarterly Tax Calculator Formula

Understand the math behind the estimated quarterly tax calculator. Each variable explained with a worked example.

Use the Estimated Quarterly Tax Calculator

Formulas Used

Quarterly Payment

quarterly_payment = (federal_tax + se_tax + taxable * state_rate / 100) / 4

Annual Tax Estimate

annual_total = federal_tax + se_tax + taxable * state_rate / 100

Effective Total Rate

effective_rate = annual_income > 0 ? (federal_tax + se_tax + taxable * state_rate / 100) / annual_income * 100 : 0

Variables

VariableDescriptionDefault
annual_incomeExpected Annual Income(USD)100000
deductionsEstimated Deductions(USD)20000
state_rateState Tax Rate(%)5
taxableDerived value= max(annual_income - deductions, 0)calculated
se_taxDerived value= annual_income * 0.9235 * 0.153calculated
federal_taxDerived value= taxable <= 11600 ? taxable * 0.10 : (taxable <= 47150 ? 1160 + (taxable - 11600) * 0.12 : (taxable <= 100525 ? 5426 + (taxable - 47150) * 0.22 : 17168.5 + (taxable - 100525) * 0.24))calculated

How It Works

Estimated Quarterly Tax Payments

Quarterly = (Federal Tax + SE Tax + State Tax) / 4

Due dates: April 15, June 15, September 15, January 15

You must make estimated payments if you expect to owe $1,000 or more in taxes for the year.

Worked Example

$100,000 income, $20,000 deductions, 5% state rate.

annual_income = 100000deductions = 20000state_rate = 5
  1. 01Taxable = $80,000
  2. 02Federal tax on $80k = ~$12,660
  3. 03SE tax = $100k x 0.9235 x 15.3% = $14,130
  4. 04State tax = $80k x 5% = $4,000
  5. 05Total = ~$30,790, Quarterly = ~$7,698

Ready to run the numbers?

Open Estimated Quarterly Tax Calculator