The calendar quarters are the four three-month blocks that divide the January-through-December year: January–March (Q1), April–June (Q2), July–September (Q3), and October–December (Q4). These blocks drive the deadlines for individual estimated taxes, employer payroll returns, and public-company financial reports, each on its own offset from the quarter’s close.
The Four Quarters and Their Dates
- Q1: January 1 through March 31
- Q2: April 1 through June 30
- Q3: July 1 through September 30
- Q4: October 1 through December 31
The quarters aren’t the same length. Q1 has 90 days in a standard year and 91 in a leap year because of February 29. Q2 has 91 days. Q3 and Q4 each have 92. Those small differences rarely matter for tax purposes but can affect interest calculations and daily accrual schedules.
Calendar Year vs. Fiscal Year
Not every organization uses the January-through-December calendar. The IRS defines a fiscal year as any 12 consecutive months ending on the last day of a month other than December.1Internal Revenue Service. Tax Years A company with a fiscal year ending March 31 treats April–June as its first quarter and January–March as its fourth. Retailers commonly end their fiscal year on January 31 or in early February so the holiday-season results land cleanly in one quarter rather than splitting across two.
Individual taxpayers generally must use the calendar year unless they maintain books on a different cycle and the IRS approves the arrangement. If you keep no formal accounting records, the IRS requires the calendar year.1Internal Revenue Service. Tax Years For the rest of this article, “quarter” means a calendar quarter.
Estimated Tax Deadlines for Individuals
If you earn income that isn’t subject to withholding, such as freelance earnings, rental income, investment gains, or retirement distributions, you likely owe quarterly estimated taxes. The IRS expects four installment payments per year, each tied to a payment period:
- Q1 income (January 1–March 31): payment due April 15
- Q2 income (April 1–May 31): payment due June 15
- Q3 income (June 1–August 31): payment due September 15
- Q4 income (September 1–December 31): payment due January 15 of the following year
The payment periods don’t align perfectly with the calendar quarters. Q2 income covers only two months rather than three, and Q3 income picks up three months to compensate. The quirk goes back to how the statute was written, and it catches some first-time filers off guard.2Internal Revenue Service. Estimated Tax
You calculate the payments on Form 1040-ES. The threshold that triggers the estimated-tax requirement is straightforward: if the tax shown on your return, after subtracting withholding credits, is $1,000 or more, you owe estimated payments.3Office of the Law Revision Counsel. 26 USC 6654 – Failure by Individual to Pay Estimated Income Tax Corporations face a separate but similar obligation with a lower threshold of $500.4Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax
The IRS is phasing individual taxpayers off the Electronic Federal Tax Payment System (EFTPS). As of October 2025, new individual accounts can no longer be created on EFTPS.gov, and all individual users are expected to transition to IRS Direct Pay or the IRS Online Account by late 2026.5Electronic Federal Tax Payment System. Welcome to EFTPS Businesses still use EFTPS for payroll and other deposits. You can also mail a check with a 1040-ES voucher, though electronic payments post faster and give you an immediate confirmation record.
Safe Harbors and the Underpayment Penalty
Missing or underpaying a quarterly installment triggers an addition to tax calculated at the federal short-term interest rate plus three percentage points.6Internal Revenue Service. 20.1.3 Estimated Tax Penalties For Q1 2026, that rate is 7%.7Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026 The penalty accrues separately on each missed installment from its due date until you pay it or file your annual return, so a late Q1 payment accumulates interest for longer than a late Q4 payment.
You can avoid the penalty entirely by hitting one of two safe harbors. The first is paying at least 90% of the tax you actually owe for the current year across your four installments. The second is paying at least 100% of last year’s tax liability. If your adjusted gross income exceeded $150,000 in the prior year ($75,000 if married filing separately), that 100% figure rises to 110%.3Office of the Law Revision Counsel. 26 USC 6654 – Failure by Individual to Pay Estimated Income Tax The prior-year safe harbor is useful when current-year income is hard to predict. Pay what you owed last year (or 110%), and the penalty doesn’t apply even if your actual bill ends up much higher.
Employer Form 941 Deadlines
Employers face their own quarterly cycle, separate from individual estimated taxes. Every employer who withholds federal income tax or pays Social Security and Medicare wages must file Form 941 after each quarter.8Internal Revenue Service. About Form 941, Employer’s Quarterly Federal Tax Return The return reports both the taxes withheld from employees’ paychecks and the employer’s matching share of Social Security and Medicare.
Form 941 is due by the last day of the month following each quarter’s close:9Internal Revenue Service. Instructions for Form 941
- Q1: April 30
- Q2: July 31
- Q3: October 31
- Q4: January 31 of the following year
If you deposited all taxes for the quarter on time and in full, you get an extra 10 days to file the return itself.9Internal Revenue Service. Instructions for Form 941 That grace period is worth remembering during quarters when cash flow is tight.
Federal unemployment tax (FUTA) runs on a related but separate schedule. You must deposit FUTA taxes by the last day of the month following any quarter in which your cumulative FUTA liability exceeds $500. If the liability stays at $500 or below, you carry it forward. Whatever remains after Q4 can be paid with your annual Form 940 by January 31.10Internal Revenue Service. Topic No. 759, Form 940 – Filing and Deposit Requirements
Public Company 10-Q Deadlines
Public companies on a calendar-year cycle must file quarterly financial reports with the SEC after each of the first three quarters. No 10-Q is required for Q4 because the annual report (Form 10-K) covers that period instead.
The filing deadline for a 10-Q depends on the company’s size, measured by public float:
- Large accelerated filers (public float of $700 million or more): 40 days after quarter end11U.S. Securities and Exchange Commission. Accelerated Filer and Large Accelerated Filer Definitions
- Accelerated filers (public float of $75 million to under $700 million): 40 days after quarter end
- Non-accelerated filers (public float below $75 million): 45 days after quarter end
These deadlines come directly from the form’s instructions.12Securities and Exchange Commission. Form 10-Q The 10-Q is an unaudited snapshot showing the company’s balance sheet, income statement, and cash flows for the quarter. The annual Form 10-K carries a longer deadline because it includes audited financial statements: 60 days after fiscal year end for large accelerated filers, 75 days for accelerated filers, and 90 days for non-accelerated filers.
When a Deadline Falls on a Weekend or Holiday
If any tax due date lands on a Saturday, Sunday, or legal holiday, the deadline moves to the next business day.13Internal Revenue Service. Topic No. 301, When, How and Where to File The same principle applies to SEC electronic filings. In 2026, the standard estimated-tax due dates (April 15, June 15, September 15, and January 15, 2027) all fall on weekdays, so no shifting is needed for individual filers.
One quirk worth knowing: “legal holiday” for IRS deadline purposes means a legal holiday in the District of Columbia, and those holidays affect taxpayers nationwide. The most common example is Emancipation Day, observed on April 16 in D.C. When April 16 falls on a Friday, the holiday is observed that day and April 15 remains the deadline. When it falls on a weekend, the observed date can shift to a Monday, pushing the nationwide filing deadline to April 17 or April 18.14Internal Revenue Service. Effect of Emancipation Day on Filing and Payment Deadlines In 2026, April 16 falls on a Thursday, so Emancipation Day does not push the April 15 deadline.
Employer Form 941 deadlines follow the same weekend-and-holiday rule. For 2026, the Q3 deadline of October 31 falls on a Saturday, making the return due Monday, November 2. The Q4 deadline of January 31, 2027, falls on a Sunday, shifting to Monday, February 1.9Internal Revenue Service. Instructions for Form 941
State Quarterly Obligations
Most states with an income tax require their own quarterly estimated payments, and the majority follow the federal schedule of April 15, June 15, September 15, and January 15. A few states set slightly different dates, so check your state’s revenue department if you live in one of the roughly 40 states that impose an individual income tax.
Employers also file state unemployment insurance (SUTA) reports each quarter. The standard deadline across most states is the last day of the month following the quarter’s end, matching the federal Form 941 cadence. State sales-tax returns follow a similar quarterly cycle for mid-sized businesses, though the exact filing frequency and thresholds vary. States typically assign you a monthly, quarterly, or annual filing schedule based on your tax liability or gross sales from the prior year.