AI Quarterly Tax Estimate Generator

You must pay quarterly estimated taxes if you expect to owe $1,000 or more in taxes not covered by withholding. This commonly applies to self-employed individuals, freelancers, sole proprietors, partners, S-Corp shareholders, and people with significant investment income. Even if you have a W-2 job, you need quarterly payments on income not subject to withholding. Failure to pay can result in IRS penalties.

The four quarterly deadlines are: Q1 (January-March) due April 15, Q2 (April-May) due June 15, Q3 (June-August) due September 15, and Q4 (September-December) due January 15 of the following year. If the due date falls on a weekend or holiday, the deadline moves to the next business day. Late payments incur a penalty based on the number of days late and the applicable interest rate.

The safe harbor rule protects you from underpayment penalties if you pay at least 100% of your prior year's total tax liability (110% if AGI exceeds $150,000) through estimated payments and withholding. Alternatively, paying at least 90% of your current year's tax liability also avoids penalties. Our calculator computes both options so you can choose the approach that results in the most manageable quarterly payments.

Self-employment tax is 15.3% on net self-employment income — 12.4% for Social Security (on income up to $168,600 for 2024) and 2.9% for Medicare (no cap). You first multiply net income by 92.35% (the taxable portion), then apply the 15.3% rate. You can deduct 50% of self-employment tax as an above-the-line deduction on your income tax return. Our calculator includes this in your quarterly estimate.

The IRS charges an underpayment penalty calculated using the federal short-term interest rate plus 3 percentage points, applied to each quarter's underpayment from its due date until paid. The penalty is typically relatively small but adds unnecessary cost. More importantly, large year-end tax bills create cash flow stress. Consistent quarterly payments spread the obligation evenly and avoid year-end surprises and penalties.