Estimated Quarterly Tax for a Single-Member LLC — 2026 Calendar and Worksheet

This article is for educational purposes only. It does not constitute tax advice. Consult a qualified tax professional for your specific situation.

Who Actually Owes Estimated Tax

The US federal income tax system is pay-as-you-go. Most wage employees satisfy this rule automatically — the employer withholds income tax, Social Security, and Medicare from every paycheck. LLC owners do not have withholding unless they pay themselves a W-2 salary through an S-corp election. The IRS bridges this gap with estimated quarterly tax — four scheduled prepayments that substitute for paycheck withholding.

You generally owe estimated tax for 2026 if you expect to owe at least $1,000 in federal income tax after subtracting withholding and refundable credits, and your withholding will cover less than the safe-harbor amount described below. Typical LLC situations that fall into this bucket:

• US-person single-member LLC owner — the LLC is a disregarded entity, profit flows to Schedule C, and the owner pays self-employment tax plus regular income tax on the net profit.
• Multi-member LLC partner — the partnership issues a Schedule K-1 to each member; K-1 income is not withheld on and must be covered by estimated tax.
• S-corporation shareholder with pass-through distributions — reasonable compensation paid via W-2 is withheld, but K-1 distributions above the W-2 salary are not.
• Schedule C sole proprietor earning alongside LLC activity — the same rules apply to non-LLC self-employment income.

Non-resident alien owner of a foreign-owned disregarded entity generally does NOT owe 1040-ES unless the LLC generates effectively connected income (ECI) — meaning income connected with a US trade or business. A non-resident who simply owns a Wyoming LLC that sells digital services to customers outside the United States typically has no US filing obligation beyond Form 5472 and the pro-forma 1120. Estimated tax does not apply because there is no US income tax to pay in the first place. The ECI analysis changes that conclusion, and it is covered in its own section below.

The Safe-Harbor Rules — How to Avoid the §6654 Penalty

Internal Revenue Code §6654 imposes an underpayment penalty when your quarterly prepayments fall short. The penalty is computed as an interest charge on the underpayment for each day it remained unpaid. You avoid the penalty entirely by meeting any one of three safe harbors for the year. Pay whichever of the following is smallest:

1. 90% of the current year's total tax. If your 2026 total tax liability turns out to be $40,000, paying $36,000 across the four quarterly installments satisfies the safe harbor.

2. 100% of the prior year's total tax when prior-year adjusted gross income (AGI) was $150,000 or less ($75,000 or less if married filing separately). If 2025 tax was $30,000 and 2025 AGI was $140,000, paying $30,000 in 2026 installments (regardless of how 2026 actually turns out) satisfies the safe harbor.

3. 110% of the prior year's total tax when prior-year AGI exceeded $150,000. Same example but with 2025 AGI of $200,000: the safe-harbor amount is $33,000.

The key insight is that you can choose the lowest of the three. A founder whose income is jumping from $140,000 (2025) to $400,000 (2026) can lock in the 100%-of-prior-year safe harbor and avoid computing the full 2026 liability until April 15, 2027. Conversely, a founder whose income is dropping can pay based on 90% of the expected 2026 number rather than the higher prior-year figure.

The safe harbor is satisfied only if the payments are made on schedule. Paying 110% of prior-year tax in a single lump sum on April 15, 2027 does not cure quarters 1-4 of 2026. Each quarter is evaluated independently.

2026 Due Date Calendar

For calendar-year taxpayers, the 2026 estimated tax installments are due on these four dates:

Notice that the quarters are not equal in length — Q2 covers only two months and Q3 covers three. The IRS divided the year this way decades ago and never rebalanced it. For worksheet purposes most taxpayers still split expected annual tax into four equal payments; the unequal periods only matter if you use the annualized income installment method (Form 2210 Schedule AI) to reflect uneven income.

When a due date falls on a Saturday, Sunday, or federal holiday, it shifts to the next business day. None of the 2026 estimated-tax dates fall on a weekend or holiday as published, so the dates above are final. Always verify on the IRS website before mailing a payment — regional holidays (Emancipation Day in DC, Patriots' Day in MA/ME) have shifted tax deadlines in prior years.

Q4 is the single most-missed payment. January 15 comes after the holidays, and founders who intend to "catch up at April 15" trigger a §6654 penalty even when they ultimately pay everything owed.

Forms and Payment Vehicles

For individuals (US persons and resident aliens): Form 1040-ES. The form includes four tear-off vouchers and a worksheet for computing the installment amount. You can pay:

• Electronically via IRS Direct Pay (free, debits a bank account, no registration required for individuals)
• Electronically via EFTPS (Electronic Federal Tax Payment System — requires enrollment, allows scheduling)
• Credit or debit card through an IRS-approved processor (processing fees apply)
• By check with the paper voucher, mailed to the IRS service center listed on the 1040-ES instructions for your state

Electronic payment confirms instantly and leaves a clean record. Paper checks are accepted — LLC owners in states without fast mail service should allow at least a week of transit time and keep the certified-mail receipt.

For C-corporations (LLCs that elected corporate tax treatment via Form 8832 or that are taxed as C-corps by default): Form 1120-W is the estimated-tax worksheet, and payments are submitted through EFTPS. Corporations with prior-year tax liability above de minimis thresholds are required to use EFTPS — paper checks are not accepted for corporate estimated payments.

For partnerships and S-corporations: these entities generally do not owe entity-level estimated tax federally. The income passes through and the individual partners or shareholders pay estimated tax on their personal 1040-ES. Some states (e.g., New York, California) impose entity-level pass-through taxes with their own state estimated-payment requirements.

A Worked Worksheet — US-Resident Single-Member LLC

Consider a US-resident founder who owns a Wyoming single-member LLC and expects the following for 2026:

• Net Schedule C profit: $120,000
• Other income: none
• Filing status: Single, no dependents, taking the standard deduction
• 2025 total tax: $22,000 (AGI was $118,000, so the $150k threshold was not crossed)

Step 1 — Self-employment tax. SE tax is 15.3% on 92.35% of net self-employment profit, up to the 2026 Social Security wage base (indexed annually; assume $168,600 for illustration — verify the current year's figure with the SSA). Above the wage base, only the 2.9% Medicare portion continues. With $120,000 of profit:

• SE-taxable base: $120,000 × 0.9235 = $110,820
• SE tax: $110,820 × 0.153 = $16,955
• Deductible half of SE tax (above-the-line deduction): $8,478

Step 2 — Regular income tax. Start with Schedule C profit, subtract the deductible half of SE tax, subtract the Qualified Business Income (QBI) deduction if available, subtract the standard deduction, then apply the 2026 single-filer brackets:

• Gross income: $120,000
• Less deductible half of SE tax: -$8,478
• AGI: $111,522
• Less QBI deduction (20% of qualified business income, subject to limits): ~-$20,600
• Less standard deduction (2026 single filer, indexed — use the current year's published figure): ~-$15,000
• Taxable income: ~$75,922
• Federal income tax (2026 single brackets, indexed — use published amounts): ~$11,800

Step 3 — Total 2026 estimated liability.

• SE tax: $16,955
• Income tax: $11,800
• Total: ~$28,755

Step 4 — Safe-harbor comparison.

• 90% of current year: $28,755 × 0.90 = $25,880
• 100% of prior year (AGI was below $150k): $22,000
• Safe-harbor amount = smaller = $22,000

Step 5 — Quarterly installment. $22,000 / 4 = $5,500 per quarter. Paid on April 15, June 15, September 15, and January 15, 2027. If actual 2026 tax ends up at $28,755, the final $6,755 balance is paid with the 2026 return by April 15, 2027. No §6654 penalty applies because the safe harbor was met.

The specific bracket amounts, standard deduction, and QBI phase-outs change every year. Do not copy these numbers as gospel — use them as a template for the methodology and plug in the current-year figures from IRS Publication 505 or your tax software.

Special Case — Non-Resident Owner with Effectively Connected Income

A non-resident alien who owns a Wyoming single-member LLC is outside the 1040-ES universe by default. The disregarded entity does not itself owe US income tax, and the foreign owner has no US tax liability to estimate. The combination of Form 5472 and the pro-forma 1120 satisfies federal obligations.

This changes if the LLC generates effectively connected income (ECI) — income from a US trade or business. Common fact patterns that the IRS has argued create ECI include:

• FBA inventory stored in US warehouses. Selling physical goods that sit in Amazon fulfillment centers on US soil has been a contested but increasingly common ECI trigger. Treasury and courts have not definitively resolved the question for every fact pattern, and outcomes depend on the level of US activity beyond mere storage.
• US-based employees or dependent agents. Hiring a W-2 employee in Texas or engaging a US agent who habitually concludes contracts on the LLC's behalf creates a permanent establishment under most treaties and ECI under US domestic law.
• Real property held for production of income. Rental real estate in the US is taxed as ECI by default, though the §871(d) or §882(d) election can change the mechanics.
• Active personal services performed in the US by the foreign owner during physical visits.

When ECI exists, the foreign owner files Form 1040-NR (for non-resident individuals) or the LLC files Form 1120-F (if reclassified as a foreign corporation). Estimated tax applies in the same way it applies to US taxpayers — four installments, safe harbors, §6654 penalty for underpayment. Treaty benefits generally do not override ECI taxation; tax treaties usually permit source-country taxation of business profits attributable to a permanent establishment.

The ECI analysis is fact-heavy and jurisdiction-specific. Any non-resident whose LLC has warehouse stock, US staff, or US real estate should run the question past a cross-border tax professional rather than assume the default "no ECI" position. For background on the broader compliance picture, see our Form 5472 guide and the US tax treaty overview.

Special Case — LLC Elected C-Corp Status Via Form 8832

If the LLC filed Form 8832 to elect corporate tax treatment (or defaulted to corporate status for some other reason), the analysis changes entirely. The LLC itself is now a taxpayer. It files Form 1120 reporting its own income, computes its own tax at the 21% flat corporate rate, and owes estimated tax under the rules of Form 1120-W — not 1040-ES.

Key corporate estimated-tax mechanics:

• Four installments, due on the 15th day of the 4th, 6th, 9th, and 12th months of the corporation's tax year. For calendar-year corporations that maps to April 15, June 15, September 15, and December 15 — note that December 15 is earlier than the individual Q4 date of January 15.
• Safe harbors: 100% of the current year's tax, or 100% of the prior year's tax (no 110% uplift for large corporations in most cases, though "large corporations" with $1M+ taxable income are restricted to the current-year safe harbor for the later quarters).
• Payment through EFTPS is effectively mandatory — paper checks are not a practical option for corporate estimated payments.
• Owner salaries and distributions add a second layer. The corporation withholds on W-2 wages paid to the owner-employee. Distributions to the owner as dividends are reported on Form 1099-DIV and may require separate estimated-tax planning on the owner's personal 1040-ES.

The corporate election is not reversible for five years (absent rare relief), so the estimated-tax burden that comes with it is a long-term commitment. Most small single-member LLCs do not benefit from the corporate election — the disregarded-entity default is simpler and avoids double taxation.

Common Mistakes

1. Forgetting the January 15 payment. Q4 is the quarter most commonly missed. A founder who paid faithfully in April, June, and September but settled up only at April 15, 2027 will owe §6654 penalty on the Q4 underpayment, even if the annual total was correct. The fix is a calendar reminder and, ideally, scheduled EFTPS debits for all four quarters set up in January.

2. Assuming W-2 withholding covers LLC income. A founder with a W-2 day job and a side LLC sometimes sees a small refund on the W-2 side and concludes nothing else is owed. That analysis ignores the Schedule C profit and self-employment tax entirely. You can increase W-2 withholding (Form W-4) to cover LLC income as an alternative to 1040-ES — withholding is treated as paid evenly across the year for §6654 purposes, which can paper over a missed quarter.

3. Non-resident owner assuming ECI applies when sales are purely passive. The mirror error: a non-resident who sells digital products to customers worldwide, with no US presence, sometimes mistakenly files 1040-NR with estimated payments out of an abundance of caution. This creates filing history the IRS interprets as a US trade or business, and it is difficult to unwind in later years. If you truly have no ECI, the correct position is Form 5472 + pro-forma 1120 only — not 1040-NR.

4. Ignoring state estimated tax. Wyoming has no state income tax, so a Wyoming-resident LLC owner has no state quarterly obligation. But the state residence of the owner, not the LLC's formation state, usually controls. A California resident who owns a Wyoming LLC still owes California income tax and California estimated payments (Form 540-ES). Same for New York, Oregon, and every other income-tax state. State penalties for underpayment are separate from federal penalties.

5. Using last year's worksheet without updating brackets. Standard deductions, bracket thresholds, Social Security wage bases, and QBI phase-outs are all indexed annually. Running a 2026 estimate with 2025 numbers can understate or overstate tax by several percentage points. IRS Publication 505 (Tax Withholding and Estimated Tax) is republished annually and is the authoritative reference.

If You Missed a Quarter

Pay it as soon as possible. The §6654 penalty is computed per day of underpayment, so paying 30 days late is materially cheaper than waiting until April 15. Use IRS Direct Pay or EFTPS, and label the payment with the correct quarter and tax year.

When you file the 2026 return, complete Form 2210 (Underpayment of Estimated Tax by Individuals, Estates, and Trusts). The form:

• Computes the precise penalty amount quarter by quarter
• Lets you use the annualized income installment method if your income was uneven across the year (helpful if a large chunk arrived only in Q4)
• Requests penalty waiver for reasonable cause — casualty, disaster, unusual circumstance — or under the first-time-abatement doctrine if you have a clean compliance record

Reasonable cause relief is granted at IRS discretion and is more common for taxpayers who self-correct quickly and file accurate paperwork. It is not a substitute for paying on schedule.

Cross-Link

For adjacent compliance topics, see our Form 5472 guide, the Form W-8BEN-E walkthrough, the tax calendar for foreign-owned Wyoming LLCs, and the Wyoming LLC tax advantages overview. Definitions of terms used here are in our glossary.

This article is for educational purposes only. It does not constitute tax advice. Consult a qualified tax professional for your specific situation.