Q4 is the fourth and final quarter of a 12-month reporting year. On the standard calendar, Q4 runs from October 1 through December 31. For a business or government on a fiscal year that starts in some other month, Q4 is still the last three months of its cycle, but the dates shift. When someone says “Q4” without context, they almost always mean the calendar version: October, November, and December.
Calendar Q4: October Through December
The calendar year runs January 1 through December 31, so its fourth quarter is October 1 through December 31. This is the default for most individuals, sole proprietors, and small businesses that haven’t elected a different reporting period.
The IRS organizes its own tax calendar around this structure, listing October, November, and December as the fourth quarter’s months.1Internal Revenue Service. Fourth Quarter – Tax Calendar Financial news coverage, holiday retail forecasts, and year-end investment commentary all reference this same October-through-December window.
Fiscal Year Q4: When the Dates Shift
A fiscal year is any 12-consecutive-month period a business adopts for accounting and tax purposes. For IRS purposes, a fiscal year ends on the last day of any month other than December, since a December 31 ending is simply a calendar year.2Internal Revenue Service. Publication 538, Accounting Periods and Methods Wherever the fiscal year starts, Q4 is the last three months of it.
A few common patterns:
- A February 1 fiscal year start, used by many major retailers including Walmart and Target, puts Q4 at November 1 through January 31. The cycle captures the entire holiday selling season inside one reporting year rather than splitting it across two.
- A July 1 fiscal year start, common among nonprofits and universities, puts Q4 at April 1 through June 30. It aligns reporting with the school year or grant funding cycles.
- An October 1 fiscal year start, which the federal government uses, puts Q4 at July 1 through September 30. Some private contractors that depend heavily on government work adopt the same cycle.
The flexibility exists so management can close the books at a natural low point in activity. A retailer that closed on December 31 would be reconciling its busiest month while simultaneously preparing year-end financial statements; ending in January gives the accounting team breathing room after the holiday rush.
The Federal Government’s Q4: July Through September
The U.S. federal government operates on a fiscal year that begins October 1 and ends September 30.3USAGov. The Federal Budget Process That makes the government’s Q4 the period from July 1 through September 30, out of phase with the calendar Q4 most people picture.
The timing creates a well-documented year-end spending surge. Agencies that haven’t spent their full annual appropriation face pressure to obligate remaining funds before September 30, because unspent money generally returns to the Treasury. Roughly 16 percent of annual executive branch contract spending occurs in September alone, nearly double what an even distribution would predict.4Mercatus Center. Curbing Wasteful Year-End Federal Government Spending: Reforming “Use It or Lose It” Rules If you sell to the federal government, July through September is when contract opportunities peak.
Q4 Tax Deadlines After the Calendar Year Closes
The close of calendar Q4 triggers a wave of federal tax deadlines in January and February. Missing them can trigger penalties.
Estimated Tax Payments
Individuals who expect to owe $1,000 or more in federal tax for the year (after subtracting withholding and refundable credits) generally must make quarterly estimated payments using Form 1040-ES. Corporations facing a tax liability of $500 or more use Form 1120-W.5Internal Revenue Service. Estimated Taxes
One wrinkle catches people off guard: the IRS “quarters” for estimated tax are not four equal three-month periods. The fourth payment period covers September 1 through December 31, a full four months, and its payment is due January 15 of the following year.6Internal Revenue Service. When to Pay Estimated Tax You can skip the January 15 payment entirely if you file your complete tax return and pay any balance due by February 1.7Internal Revenue Service. Form 1040-ES (2026)
If you underpay during the year, the IRS charges a penalty calculated as interest on the shortfall. The underpayment rate is the federal short-term rate plus three percentage points, compounded daily. For the first quarter of 2026, that rate is 7 percent.8Internal Revenue Service. Quarterly Interest Rates You can avoid the penalty by paying at least 90 percent of the current year’s tax or 100 percent of the prior year’s tax, whichever is less. If your adjusted gross income exceeded $150,000 in the prior year ($75,000 if married filing separately), that prior-year safe harbor rises to 110 percent.9Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty
Payroll and Employment Taxes
Employers file Form 941, the quarterly federal return for withheld income tax, Social Security, and Medicare, by the last day of the month after each quarter closes. For Q4, that means January 31. If you deposited all employment taxes on time throughout the quarter, you get an extra 10 calendar days to file.10Internal Revenue Service. Employment Tax Due Dates
The annual federal unemployment tax return, Form 940, follows shortly after. For the 2025 tax year, the deadline falls on February 2, 2026, with a 10-day extension available if all FUTA deposits were made on time. If your fourth-quarter FUTA liability plus any undeposited amounts from earlier quarters exceeds $500, you must deposit the full amount by the same February deadline.11Internal Revenue Service. Instructions for Form 940 (2025)
1099s and Other Information Returns
Businesses that paid independent contractors, distributed retirement funds, or made other reportable payments during the year must issue information returns after Q4 closes. Form 1099-NEC (nonemployee compensation) must be furnished to recipients and filed with the IRS by January 31. Most other 1099 variants, including 1099-MISC, 1099-INT, and 1099-R, must be sent to recipients by January 31, though the IRS filing deadline for those forms is February 28, or March 31 if filed electronically.12Internal Revenue Service. Publication 1099, General Instructions for Certain Information Returns (2026)
Q4 for Public Companies: No Separate Quarterly Report
Publicly traded companies do not file a separate quarterly report for Q4. Fourth-quarter results are rolled into the annual report on Form 10-K, which provides audited financial statements covering the full fiscal year.13Legal Information Institute. Form 10-K The filing deadline depends on the company’s size:
- Large accelerated filers (public float of $700 million or more): 60 days after fiscal year-end.
- Accelerated filers (public float of $75 million to $700 million): 75 days after fiscal year-end.
- Non-accelerated filers (below $75 million): 90 days after fiscal year-end.
For the first three quarters, companies file the shorter Form 10-Q, which is unaudited. Large accelerated and accelerated filers have 40 days after quarter-end; non-accelerated filers have 45 days. Q4 has no 10-Q. The 10-K replaces it, which is why the annual report takes longer to prepare: auditors review the full year, not just one quarter. Q4 earnings calls typically happen within a few weeks of the quarter’s close, well before the 10-K itself is filed, and often move stock prices more than the formal filing because they include forward-looking management commentary that the SEC document does not.
Why Q4 Carries So Much Weight
For consumer-facing businesses on a calendar year, the October-through-December window often decides the full year’s results. Holiday spending drives the bulk of yearly sales for retailers, and many companies depend on Q4 to cross from loss into profit.
Internally, Q4 is when most organizations finalize the operating budget for the following year. Capital expenditure requests, headcount plans, and departmental allocations get locked in. Companies also conduct physical inventory counts near fiscal year-end to reconcile what’s on the shelves with what’s in the accounting system, a basic requirement under generally accepted accounting principles, and the results feed directly into the annual financial statements.
For businesses on a non-calendar fiscal year, these same pressures simply shift to match. A company ending its fiscal year on June 30 runs through the same budget finalization and inventory reconciliation during its own Q4 in April through June. The calendar date changes; the intensity of year-end close does not.