Educational content only. Federal deadlines only. This calendar covers federal tax deadlines as generally published by the IRS. It is not tax advice. Most states have separate estimated tax deadlines that differ from federal due dates—check your state tax agency website for state-specific requirements. Consult a licensed CPA for guidance specific to your business, state, and tax situation.
Missing a tax deadline does not just result in a fine. Two separate penalty clocks start running simultaneously—one for filing late, one for paying late—and interest compounds daily on the unpaid balance. For a sole proprietor with a $3,000 tax bill left unpaid for four months, the combined penalties add up to roughly $615 before interest, on a bill that was already owed.
The solution is not a better memory. It is a system: deadlines on a calendar, quarterly payments on autopilot, and a bookkeeping template that produces accurate numbers when you need them. This guide provides the calendar. The rest follows from it.
Q2 estimated taxes are due June 15, 2026 — 37 days from now. This is the single most commonly missed deadline for new sole proprietors. If you made money in April or May and have not set aside your estimated payment, that is the place to start.
The Master 2026 Tax Deadline Calendar
All dates below are federal. Where a date falls on a weekend or federal holiday, the IRS moves the deadline to the next business day (indicated in parentheses). State deadlines vary—verify yours separately.
| Date | Deadline | Who It Affects |
|---|---|---|
| Jan 15, 2026 (Wed) | Q4 2025 estimated tax payment | Sole props, self-employed, partners |
| Jan 31, 2026 → Feb 2 (Mon) | 1099-NEC filed with IRS + recipient copies sent | Any biz that paid contractors $600+ |
| Feb 28, 2026 (Sat) → Mar 2 (Mon) | 1099-MISC paper filing with IRS | Paper filers only (e-file by Mar 31) |
| Mar 15, 2026 → Mar 16 (Mon) | S-Corp (Form 1120-S) + Partnership (Form 1065) | S-corps, multi-member LLCs, partnerships |
| Mar 31, 2026 (Tue) | 1099-MISC electronic filing with IRS | E-filers with 1099-MISC to submit |
| Apr 15, 2026 (Wed) | Personal return (Form 1040) + Schedule C | Sole props, single-member LLCs |
| Apr 15, 2026 (Wed) | Q1 2026 estimated tax payment | Sole props, self-employed, partners |
| Apr 15, 2026 (Wed) | C-Corp (Form 1120) + FBAR (FinCEN 114) | C-corporations, foreign account holders |
| Jun 15, 2026 (Mon) | Q2 2026 estimated tax payment | Sole props, self-employed, partners |
| Jul 31, 2026 (Fri) | Q2 payroll (Form 941) | Employers with W-2 employees |
| Sep 15, 2026 (Tue) | Q3 2026 estimated tax payment | Sole props, self-employed, partners |
| Sep 15, 2026 (Tue) | Extended S-Corp (1120-S) + Partnership (1065) | S-corps / partnerships that filed Form 7004 |
| Oct 15, 2026 (Thu) | Extended personal return (Form 1040) | Sole props who filed Form 4868 by Apr 15 |
| Jan 15, 2027 (Fri) | Q4 2026 estimated tax payment | Sole props, self-employed, partners |
Past deadlines shown in gray. June 15 (Q2) is the next live deadline for most sole proprietors.
Quarterly Estimated Taxes: The Mechanics
Quarterly estimated taxes are the most common source of surprise bills for new small business owners. Without an employer withholding on your behalf, you owe the IRS four times per year—and the schedule is not evenly spaced.
The Q2 Anomaly: Two Months, Not Three
The IRS quarterly calendar is not four equal quarters. Q2 covers only April and May—two months of income. Q4 covers four months (September through December). This matters because a business owner who divides their annual tax estimate by four and pays it in equal quarters will underpay in Q4 and overpay in Q2, which can still trigger penalties if the Q4 payment is insufficient.
The cleaner approach is to pay based on actual income earned in each period, or to use the safe harbor method (described below), which eliminates underpayment penalties regardless of how your income is distributed.
Safe Harbor: How to Avoid Underpayment Penalties
The IRS underpayment penalty does not apply if you satisfy either of these thresholds—you only need to meet one, not both:
- Option A: Pay at least 90% of your actual 2026 tax liability across the four quarters
- Option B: Pay at least 100% of your 2025 tax liability (110% if your 2025 adjusted gross income exceeded $150,000)
Option B is the simpler path for most sole proprietors: look at last year’s Form 1040, find total tax (line 24), divide by four (multiply by 1.10 first if 2025 AGI exceeded $150K), and pay that equal amount each quarter. You know the number on day one, before a single dollar of 2026 income arrives. Important: safe harbor is evaluated per quarter—divide your prior-year total into four equal installments. Paying a lump sum late in the year can still trigger a quarterly underpayment penalty even if the annual total meets the threshold.
Safe harbor worked example: Your 2025 total tax was $8,400. Safe harbor quarterly payment (AGI ≤$150K): $8,400 ÷ 4 = $2,100/quarter. Pay $2,100 on Apr 15, Jun 15, Sep 15, and Jan 15, 2027 — no underpayment penalty, regardless of what your 2026 income actually is. If AGI >$150K: $8,400 × 1.10 = $9,240 ÷ 4 = $2,310/quarter.
The 1099-NEC: A February Trap for Small Businesses
If your business paid any contractor, freelancer, or unincorporated service provider $600 or more in 2025, you were required to issue Form 1099-NEC. Both the recipient copy and the IRS filing were due January 31—which fell on a Saturday in 2026, shifting the deadline to February 2.
This deadline is distinct from the income tax filing deadline. The IRS treats missing or late 1099s as a separate offense with its own penalty schedule: $60 per form if filed within 30 days, up to $310 per form for intentional disregard. For a business with 10 contractors, willful noncompliance can add $3,100 in penalties before any income tax is considered.
The practical fix: collect W-9 forms from every contractor before the first payment. With a completed W-9 on file, issuing 1099s at year-end is a 30-minute data entry task, not an emergency research project.
Penalty Math: What Missing a Deadline Actually Costs
The IRS runs two penalty clocks independently. Both start the day after the deadline, and both compound on the unpaid tax balance.
| Penalty Type | Rate | Maximum | Trigger |
|---|---|---|---|
| Late filing | 5% of unpaid tax per month | 25% (5 months) | Return not filed by deadline |
| Late payment | 0.5% of unpaid tax per month | 25% (50 months) | Tax not paid by deadline |
| Combined (both) | 5% total/month (4.5% filing + 0.5% payment) | 25% combined cap | Neither filed nor paid |
| Underpayment | Fed short-term rate + 3 pts (currently ~7–8% annualized) | No cap | Quarterly estimated payment too low |
| 1099 (per form, <30 days late) | $60 flat | $630,500/year | Late or missing 1099-NEC/MISC |
Penalty rates above reflect 2026 IRS schedules and are subject to annual adjustment. Verify current rates at IRS.gov before relying on these figures.
Late payment: $3,000 × 0.5% × 4 months = $60
Interest: ~$15 at 7.5% annualized
Total penalty: ~$615 on a bill that was already $3,000
This does not include any underpayment penalty on the underlying quarterly shortfall.
The late filing penalty is five times the late payment penalty per month. The single highest-ROI tax action for most sole proprietors is to file on time—even if you cannot pay in full. Filing stops the 4.5% monthly clock; the 0.5% payment penalty continues, but the total rate drops from 5% to 0.5%.
Track Every Deduction. Know Your Numbers Before June 15.
The Small Business Bookkeeping Template captures every expense category, calculates your YTD net income, and gives you the accurate profit number you need to calculate each quarterly payment.
Entity Type Quick Reference
Your business structure determines which forms you file and when. The table below covers the most common structures for small businesses under $1 million in revenue.
| Entity Type | Primary Return | Return Due | Estimated Taxes |
|---|---|---|---|
| Sole proprietorship | Schedule C (with Form 1040) | April 15 (Oct 15 extended) | Yes — quarterly Form 1040-ES |
| Single-member LLC (disregarded) | Schedule C (with Form 1040) | April 15 (Oct 15 extended) | Yes — same as sole prop |
| Multi-member LLC (default) | Form 1065 (partnership) | March 15 (Sep 15 extended) | Partners pay individually |
| S-Corporation | Form 1120-S | March 15 (Sep 15 extended) | Shareholders pay individually |
| C-Corporation | Form 1120 | April 15 (Oct 15 extended) | Corp pays estimated taxes directly |
Most small business owners reading this are sole proprietors or single-member LLCs—both treated identically for federal income tax purposes. Your business income appears on Schedule C, which attaches to your personal Form 1040. You pay quarterly estimated taxes on Form 1040-ES. The S-corp election is occasionally worth analyzing as revenue grows beyond $80,000–$100,000 in net income, due to the self-employment tax treatment of owner compensation. For the mechanics of self-employment tax, see the SE Tax Calculator guide.
Extensions: File vs. Pay
Filing Form 4868 by April 15 grants sole proprietors a six-month extension to file—moving the return deadline to October 15. What it does not grant is additional time to pay.
If you owe $4,000 and file an extension but do not pay by April 15, the 0.5% late payment penalty accrues on the $4,000 balance from April 16 forward. Over six months: $4,000 × 0.5% × 6 = $120 in late payment penalties, plus daily compounding interest. The extension eliminates the 4.5% per month filing penalty but not the payment obligation.
The right use of an extension: file it when you do not yet have the information to prepare an accurate return (waiting on a K-1, resolving a disputed 1099, etc.), and pay your best estimate of what you owe by April 15. An extension on a zero-tax-due return costs nothing and carries no risk.
A 5-Step System to Never Miss a Deadline
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1Add all four estimated tax dates to your calendar right now
Jun 15, Sep 15, Jan 15 (2027). Set a reminder 14 days before each one. The 14-day buffer is when you calculate the payment amount, not when you scramble to find it.
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2Open an IRS Direct Pay account (free, no software required)
IRS Direct Pay accepts same-day payments from any bank account. The payment posts instantly and generates a confirmation number. No check, no mail, no risk of a lost payment causing a late penalty on a bill you thought you paid.
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3Decide: safe harbor or actual income method
Safe harbor is simpler. Look up your 2025 total tax (Form 1040, line 24). Divide by four (multiply by 1.10 first if AGI >$150K). That is your quarterly payment—no calculation needed each quarter, no penalty possible. The actual income method is more accurate if your income is low or lumpy.
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4Keep a running monthly P&L
Quarterly estimated taxes require knowing your net income. A bookkeeping template that closes monthly gives you that number in under 30 minutes—accurate enough to calculate both the actual method payment and verify your safe harbor amount. Without monthly bookkeeping, you are estimating an estimate.
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5Collect W-9s before paying any contractor
The 1099-NEC is not optional once you cross the $600 threshold. Making W-9 collection a condition of first payment means you always have the information you need in January when 1099s are due—not the week before the deadline when contractors are unreachable.
Related Guides in the Small Business Cluster
Each deadline in this calendar links to a financial system. The guides below cover the underlying mechanics.
Frequently Asked Questions
The four quarterly estimated tax deadlines for 2026 are: April 15 (Q1, covering January–March income), June 15 (Q2, covering April–May income only—two months, not three), September 15 (Q3, covering June–August income), and January 15, 2027 (Q4, covering September–December income). Q1 and April 15 have already passed. The next deadline for most sole proprietors is June 15.
Two separate penalties run simultaneously. The late filing penalty is 5% of unpaid tax per month (or partial month), capped at 25% after five months. The late payment penalty is 0.5% per month, also capped at 25%. When both apply, the IRS reduces the filing penalty to 4.5%, making the combined rate 5%/month. Interest accrues on top at the federal short-term rate plus 3 percentage points. A $3,000 unpaid bill four months past deadline carries approximately $615 in combined penalties before interest. Filing on time—even without paying—stops the 4.5% filing penalty clock and drops the monthly cost from 5% to 0.5%.
Generally yes, if you expect to owe $1,000 or more in federal tax for the year. Sole proprietors and single-member LLC owners have no employer withholding—that obligation is replaced by four quarterly payments on Form 1040-ES. To avoid underpayment penalties, satisfy either of two safe harbor thresholds—you only need to meet one: pay at least 90% of your 2026 tax liability, or pay at least 100% of your 2025 tax (110% if 2025 AGI exceeded $150,000). Safe harbor is evaluated per quarter; divide your prior-year total into four equal installments for the cleanest approach. The prior-year method is simpler because you know the payment amount before the year starts.
Yes. Filing Form 4868 by April 15 extends the filing deadline to October 15. However, an extension to file is not an extension to pay. Any tax owed is still due April 15. If you owe and pay after April 15, the 0.5% late payment penalty accrues on the unpaid balance from April 16 onward. The extension only stops the 5% late filing penalty from running. The correct approach: estimate what you owe, pay that amount by April 15, then file the complete return by October 15 once you have accurate numbers.
Stop Calculating Quarterly Taxes From Memory
The Small Business Bookkeeping Lite template tracks every revenue and expense category monthly—so when June 15 arrives, you have an accurate YTD net income number, not a guess. The Pro dashboard adds a 13-week cash flow model, P&L, and break-even so every quarterly payment is calibrated, not estimated.