KalkWise
Tax

Estimated Quarterly Tax Calculator

Estimate your quarterly tax payments and avoid underpayment penalties.

Updated June 2026 · Editorial standards

Income & tax details

$
$
%
$
Quarterly payment
$4,899
Estimated annual tax
$19,597
Net taxable income
$75,000
Safe-harbor quarterly
$3,500

Pay about $4,899 each quarter ($19,597/year total) to cover self-employment and income tax.To guarantee you avoid an underpayment penalty, you can instead pay the safe-harbor amount of $3,500/quarter ($14,000/year), based on last year's tax. Quarterly deadlines: Apr 15, Jun 15, Sep 15, Jan 15.

By the KalkWise Editorial Team Reviewed for accuracy Updated June 2026

What is the estimated quarterly tax calculator?

In short

Self-employed taxpayers must pay estimated taxes quarterly. On $90,000 of income with $15,000 in expenses, net income is $75,000 — about $10,600 in self-employment tax plus $9,000 in income tax (12%), so roughly $4,900 per quarter. The safe-harbor amount (based on last year's tax) avoids penalties.

Estimates your annual self-employment and income tax, divides it into quarterly payments, and computes the safe-harbor amount that protects you from underpayment penalties.

How to use this calculator

  1. 1Enter your expected annual self-employment income and business expenses.
  2. 2Set your income tax rate (separate from self-employment tax).
  3. 3Enter last year's total tax for the safe-harbor calculation.
  4. 4See your quarterly payment and the penalty-proof safe-harbor amount.

The formula

annualTax=(netSE×14.13%)+(netSE×rate)
quarterly=annualTax4
annual tax = (netSE × 0.9235 × 0.153) + (netSE × rate); quarterly = annual tax / 4
netSE
— Net income = income − expenses
SE tax
— netSE × 92.35% × 15.3%
income tax
— netSE × rate
quarterly
— (SE tax + income tax) / 4

Worked example

The scenario

$90,000 income, $15,000 expenses, 12% income tax rate, $14,000 last-year tax.

gives

The result

Net income: $75,000. Annual tax: ~$19,600. Quarterly: ~$4,900. Safe-harbor: ~$3,850/quarter.

Common use cases

  • Freelancers and independent contractors paying quarterly estimated taxes.
  • Side-hustlers who owe more than $1,000 in tax beyond withholding.
  • Avoiding IRS underpayment penalties via the safe-harbor rule.

Limitations & assumptions

  • Uses a flat income tax rate rather than graduated brackets.
  • Does not account for the deductible half of self-employment tax or QBI deduction.
  • Does not include state estimated taxes, which may also be due quarterly.

Frequently asked questions

Anyone who expects to owe $1,000 or more in tax beyond withholding — typically the self-employed, freelancers, and investors with significant untaxed income.

Disclaimer: KalkWise calculators are provided for general informational and educational purposes only and do not constitute financial, investment, tax, or legal advice. Results are estimates based on the figures you enter and the assumptions described above. Actual outcomes will vary. Consult a qualified professional before making financial decisions.