Tax

Quarterly Estimated Tax for Self-Employed and Business Owners

If you're not on a W-2, the IRS expects four prepayments a year. Miss them and you owe penalties even if you pay in full at filing.

By Aparna Devalla, CPA3 min · 5 slidesUpdated May 4, 2026

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Who Has to Pay Estimates

Anyone who expects to owe $1,000+ in tax after withholding and refundable credits: typically the self-employed, partners, S-corp shareholders, landlords, and high-investment-income earners.
If your withholding (W-2 spousal income, RSU vests, pension) covers the safe harbor, you may not need to make estimates, even on substantial business income.
Corporations have their own estimated tax rules (Form 1120-W), separate from this.
First-year businesses without prior-year tax liability are technically exempt, but it's still smart to set aside cash.

The Safe Harbor Rules

Pay at least 90% of current year tax, OR 100% of prior year tax (110% if prior year AGI > $150K), whichever is less.
Most owners use the 100%/110% safe harbor because it's predictable: take last year's total tax, divide by 4, and send it in.
If your income jumped significantly, the prior-year safe harbor still protects you, even if you owe a big amount at filing.
Penalty is calculated quarter by quarter; paying everything in Q4 doesn't fix missed Q1/Q2/Q3 payments.

How to Calculate

Method 1 (Safe Harbor): take last year's federal tax (line 24 of 1040), multiply by 100% (or 110% if AGI > $150K), divide by 4.
Method 2 (Annualized Income): use Form 2210 to recalculate quarterly based on actual income through that quarter, useful if income is lumpy.
Don't forget state estimates: California requires 30/40/0/30 (yes, 0 for Q3) on different dates.
Self-employment tax (15.3% on the first $184,500 in 2026, adjusted annually) is part of federal tax owed; include it in the calculation.
If you have RSUs vesting irregularly, increase the W-2 withholding to absorb that liability instead of estimates.

Practical Tips

Open a separate tax-savings account and transfer ~25–35% of every business deposit. The estimates effectively pay themselves.
Pay via IRS Direct Pay or EFTPS: free, with immediate confirmation. Mailing a check invites timing risk.
California uses Web Pay; most states have similar online portals.
Underpayment penalty is currently around 8% APR (adjusts quarterly with federal rates). Not catastrophic but not free.
Need help with quarterly estimates? Rubric Financial handles federal and multi-state estimates as part of every tax engagement.

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Educational content, not tax, legal, or accounting advice. Confirm with a CPA before acting.

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