2026 Quarterly Estimated Tax Calculator — Business Owners
Q2 estimated taxes are due June 15, 2026. If you're a sole proprietor, LLC owner, S-corp owner, or partner, the IRS expects quarterly payments on your business income — no employer withholds for you. Miss a deadline and the underpayment penalty (IRC §6654) accrues from the due date at roughly 7–8% annualized on the unpaid amount. Enter your 2026 numbers below to see what you owe and when.
- Q1 — April 15, 2026 (income Jan 1 – Mar 31) — already past
- Q2 — June 15, 2026 (income Apr 1 – May 31) — due in 15 days
- Q3 — September 15, 2026 (income Jun 1 – Aug 31)
- Q4 — January 15, 2027 (income Sep 1 – Dec 31)
How Estimated Taxes Work for Business Owners
When you work for an employer, they withhold income tax and FICA from every paycheck on your behalf. Business owners are their own payer — the IRS requires you to send quarterly installments of what you'll owe. If you underpay, the penalty under IRC §6654 accrues on the shortfall from the due date, not just at year-end filing.
The two ways to avoid the penalty
You're penalty-safe if you pay either of the following by each quarterly deadline:1
| Method | How it works | Best when… |
|---|---|---|
| 90% of current year tax | Pay at least 90% of your actual 2026 tax by year-end, spread across 4 quarters | Income is about the same as last year or lower |
| 100% / 110% of prior year tax | Pay 100% of your 2025 tax (110% if 2025 AGI exceeded $150,000), regardless of how 2026 turns out | Income is growing significantly — locks in a known, penalty-free floor |
Use whichever produces a lower required payment. The safe harbor (prior-year) method is popular with business owners whose income fluctuates — you know exactly what you must pay, even if 2026 turns out to be a record year.
Sole prop and partnership: self-employment tax first
Before income tax, sole props and partners owe self-employment tax — the equivalent of both the employer and employee FICA contributions that W-2 workers split with their employer. For 2026:2
- 12.4% Social Security on net self-employment earnings up to $184,500 (the 2026 SS wage base)
- 2.9% Medicare on all net self-employment earnings — no cap
- 0.9% Additional Medicare Tax on earnings above $200,000 single / $250,000 MFJ
The SE tax base is net profit × 92.35% — the 7.65% reduction accounts for the deductible employer-equivalent portion. Half of SE tax is then deductible above-the-line, reducing AGI and therefore income tax.
At $250,000 net profit: SE tax ≈ $184,500 × 12.4% + ($250,000 × 0.9235 × 2.9%) ≈ $22,878 + $6,695 = $29,573. A sole prop netting $250K pays more than $29K just in SE tax before income tax. This is one of the primary reasons advisors recommend S-corp election once income reaches $75K–$100K+.
S-corp owners: no SE tax on the K-1, but quarterly income tax still required
S-corp owners pay FICA only on their W-2 wages — distributions and K-1 pass-through income escape SE tax entirely. That's the well-known FICA savings. The tradeoff: no employer withholding on K-1 income means you must make quarterly estimated payments for the income tax owed on that K-1 income.
If your S-corp generates $300K and you pay yourself a $90K W-2 salary, your K-1 is roughly $210K. No FICA on the $210K, but you owe income tax on it quarterly. At a 32–37% marginal rate, that's $67K–$78K in income tax on K-1 income alone — due in four quarterly installments.
→ See how much you'd save with S-corp election: S-Corp vs LLC FICA Savings Calculator.
The Section 199A QBI deduction reduces your quarterly obligation
Most pass-through business owners can deduct 20% of qualified business income under § 199A. For 2026, the deduction phases out beginning at $403,500 MFJ / $201,750 single for specified service businesses (law, consulting, financial services, etc.), with a $150,000 / $75,000 phaseout range (OBBBA-expanded).3
At $250K net business income with a full 20% QBI deduction: you shelter $50,000 from income tax — worth $16,000–$18,500 at the 32–37% marginal rate. This calculator applies a simplified 20% QBI deduction for non-SSTB income below the phaseout threshold. For precise QBI modeling (SSTB, W-2 wage limitation, OBBBA phaseout): use the QBI Deduction Calculator.
Retirement plan contributions cut your estimated tax further
Solo 401(k) contributions reduce your taxable income dollar-for-dollar — and unlike estimated taxes, you can make them up to the tax filing deadline (April 2027 for 2026 returns, with extension). The plan must exist before December 31, 2026 to make 2026 contributions. At a 37% rate, the maximum Solo 401(k) contribution of $72,000 (2026) saves $26,640 in federal income tax — plus reduces SE tax slightly via lower AGI. High earners can stack a Cash Balance Plan on top, sheltering an additional $80K–$300K+.
→ Calculate your max contribution: Retirement Plan Comparison Calculator.
Get matched with a tax-aware advisor
Quarterly estimated taxes are just the payment mechanism. The real planning is in reducing the underlying tax: the right retirement plan, S-corp election, QBI optimization, bonus depreciation timing, and PTET election can collectively cut a business owner's annual tax bill by $40,000–$120,000+. A fee-only advisor specializing in business owners models the full picture — not just the quarterly check.
Frequently Asked Questions
What happens if I miss the June 15 Q2 deadline?
The IRS assesses an underpayment penalty on the shortfall for Q2 from June 15 through the date you eventually pay (or September 15 for Q3). The penalty rate is the federal short-term AFR + 3 percentage points — currently around 7–8% annualized. It's not catastrophic on small shortfalls, but on a $20,000 Q2 underpayment it can add up to $350–$400 per quarter of delay. Pay by June 15 even if you can't compute the exact amount — the penalty is on the underpayment, not for being slightly off.
Can I make one big payment in April instead of quarterly?
No — the IRS requires payments by each quarterly deadline, not just a year-end lump sum. Paying 100% of your annual liability by January 15 avoids the Q4 penalty but not the Q1–Q3 penalties on prior missed quarters. Each quarter is calculated independently.
My S-corp pays me a salary. Do I still owe estimated taxes?
Maybe. Your W-2 salary has FICA and income tax withheld. If your W-2 withholding covers 100%/110% of last year's tax or 90% of this year's tax, you may owe little or nothing quarterly. But if the majority of your S-corp income flows as K-1 distributions — with zero withholding on that portion — you almost certainly owe quarterly estimated taxes on the K-1 income. A common mistake: S-corp owners assume their W-2 withholding covers everything, then face a large balance due (plus penalties) in April.
How do I pay?
IRS Direct Pay (free) or EFTPS (Electronic Federal Tax Payment System) are the easiest options. EFTPS requires enrollment 5–7 business days before first use — if you haven't enrolled, do it now before the June 15 deadline. You can also pay by check (Form 1040-ES voucher) or credit card (fees apply).
Should I pay the current-year estimate or the safe harbor amount?
Pay whichever is lower. If your 2026 income is tracking similar to 2025, the 90%-of-current-year method may match the safe harbor. If your 2026 income is significantly higher than 2025 (you closed a big deal, sold an asset, raised prices), paying only the safe harbor (100% or 110% of prior year) still protects you from penalty — even if you end up with a large balance due in April. That flexibility is valuable in a high-income year.
Do I need to pay state estimated taxes too?
Most states with an income tax require their own quarterly estimated payments, on roughly the same schedule. California, New York, New Jersey, and most other states have quarterly deadlines — sometimes with state-specific quirks (California's Q4 is due January 15, same as federal; New York's aligns as well). Your state's revenue department website has the payment portal and schedule. Don't confuse PTET payments (entity-level) with your personal state estimated tax.
- IRS, "Estimated Tax for Individuals" (Form 1040-ES and related guidance): IRS.gov — About Form 1040-ES. The safe harbor rule (100% / 110% of prior year tax based on AGI ≤ or > $150,000) is described in IRC § 6654(d)(1)(B)(ii) and the Form 1040-ES instructions.
- Social Security Administration, "Contribution and Benefit Base": 2026 SS wage base = $184,500. SSA.gov — Contribution and Benefit Base. SE tax rates (12.4% SS + 2.9% Medicare) unchanged from prior years. Additional Medicare Tax (0.9%) per IRC § 3103, threshold $200,000 single / $250,000 MFJ per IRS Topic 560.
- IRS Rev. Proc. 2025-32 (2026 inflation adjustments): § 199A phaseout thresholds $201,750 / $403,500 for single/MFJ. OBBBA (One Big Beautiful Bill Act, July 2025): widened phaseout range to $75,000 / $150,000 (single/MFJ) and made the § 199A deduction permanent. See IRS 2026 Inflation Adjustments.
- IRS, "When to Pay Estimated Tax": quarterly due dates Q1 April 15 / Q2 June 15 / Q3 September 15 / Q4 January 15 (following year). IRS.gov — When to Pay Estimated Tax. Penalty under IRC § 6654 accrues from each quarterly due date on underpaid amounts.
Tax values verified as of May 2026 against SSA.gov (SS wage base), IRS Rev. Proc. 2025-32 (brackets, standard deductions, QBI thresholds), and OBBBA (July 2025) for QBI phaseout range changes.