Fiscal quarter end dates depend on when the fiscal year begins. For calendar-year filers, which covers most individuals and small businesses, the quarters end on March 31, June 30, September 30, and December 31. For anyone on a non-calendar fiscal year, the quarters end at three-month intervals from the chosen start date, so a fiscal year beginning July 1 produces quarter ends on September 30, December 31, March 31, and June 30.
Calendar Year Quarter Ends
Most small businesses, sole proprietors, and individual taxpayers use the calendar year, which runs January 1 through December 31.1Internal Revenue Service. Tax Years Under that model, the quarter end dates never change:
- Q1 ends March 31 (covering January 1 through March 31)
- Q2 ends June 30 (covering April 1 through June 30)
- Q3 ends September 30 (covering July 1 through September 30)
- Q4 ends December 31 (covering October 1 through December 31)
These are the dates behind most “quarterly” references you’ll see in tax guidance, financial news, and business reporting, because the calendar year is the default tax year for anyone without books or an established accounting period.2Office of the Law Revision Counsel. 26 US Code 441 – Period for Computation of Taxable Income
Non-Calendar Fiscal Year Quarter Ends
A fiscal year is any 12 consecutive months ending on the last day of a month other than December.1Internal Revenue Service. Tax Years Once the start date is set, the four quarter ends fall automatically at each three-month mark.
Work an example. A business with a fiscal year starting April 1 has Q1 ending June 30, Q2 ending September 30, Q3 ending December 31, and Q4 ending March 31. Shift the start to November 1, and the quarters end January 31, April 30, July 31, and October 31.
The U.S. federal government is the most familiar non-calendar filer. Its fiscal year runs October 1 through September 30 of the following calendar year,3Congress.gov. Basic Federal Budgeting Terminology so federal fiscal quarters end December 31 (Q1), March 31 (Q2), June 30 (Q3), and September 30 (Q4). September 30 is the date agencies mean when they talk about rushing to spend budget before year-end.
Retailers often close their fiscal year in late January or early February, letting a single reporting cycle capture the holiday season along with post-holiday returns and markdowns. Colleges and universities commonly close on June 30 or August 31 to align with the academic calendar. Both patterns push the quarter ends off the standard March, June, September, December cadence.
The 52/53-Week Fiscal Year
Some companies, particularly large retailers, don’t end their fiscal year on the last day of a month. They use a 52/53-week year that always ends on the same day of the week, such as the last Saturday in January or the Friday nearest January 31.4eCFR. 26 CFR 1.441-2 – Election of Taxable Year Consisting of 52-53 Weeks The year-end date drifts by a few days from one year to the next, and roughly every five or six years an extra week is added to keep the calendar aligned.
The National Retail Federation’s 4-5-4 calendar splits each quarter into periods of four weeks, five weeks, and four weeks. Every quarter contains exactly 13 weeks, and comparable periods across years always contain the same number of each weekday. The tradeoff is that the actual quarter-end date shifts each year, and any deadlines keyed to that date, including SEC filings and internal reporting cutoffs, shift with it.
Estimated Tax Quarters Are Not the Same
One source of confusion worth flagging: the IRS estimated tax payment periods for individuals are called “quarterly” but don’t line up with calendar quarters. The four periods and due dates are:5Internal Revenue Service. Individuals 2
- Period 1 covers January 1 through March 31, with payment due April 15
- Period 2 covers April 1 through May 31 (two months), with payment due June 15
- Period 3 covers June 1 through August 31 (three months), with payment due September 15
- Period 4 covers September 1 through December 31 (four months), with payment due January 15 of the following year
Missing any due date can trigger an underpayment penalty even if you’re due a refund at year-end.5Internal Revenue Service. Individuals 2
Corporations on a fiscal year follow yet another schedule. Their estimated tax installments are due on the 15th day of the 4th, 6th, 9th, and 12th months of the tax year.6Internal Revenue Service. Publication 509 (2026), Tax Calendars For a corporation whose fiscal year starts July 1, that means installments on October 15, December 15, March 15, and June 15.
Why the Quarter End Date Matters
For publicly traded companies, the quarter-end date starts a countdown to the Form 10-Q filing. The 10-Q is required for each of the first three fiscal quarters; the annual Form 10-K covers Q4.7Investor.gov. Form 10-Q Large accelerated filers and accelerated filers have 40 days after quarter end to file; all other filers have 45 days.8U.S. Securities and Exchange Commission. Form 10-Q General Instructions A company that can’t meet the deadline can file Form 12b-25 by 5:30 p.m. Eastern the next business day after the original due date, which buys an additional five calendar days.
Lenders also key covenants to quarter ends. A commercial loan might require the borrower to hold a debt-service coverage ratio of at least 1.25 at the close of every fiscal quarter. Dropping below that threshold on the measurement date, even briefly, can trigger default provisions. The exact quarter-end date, not an approximation, is what the covenant tests against.
Internally, quarter end is the point when management freezes the books, cuts off revenue recognition, counts inventory, and books accruals. On a 52/53-week year, where the date moves each year, the accounting team has to coordinate cutoff procedures around a shifting target.
Who Can Actually Choose a Non-Calendar Fiscal Year
Not every business gets to pick freely. The IRS imposes a required tax year on several common entity types:
- S corporations must use the calendar year unless they can show the IRS a legitimate business purpose for a different year. Income deferral to shareholders is not a valid purpose.9Office of the Law Revision Counsel. 26 US Code 1378 – Taxable Year of S Corporation
- Partnerships generally must adopt the tax year of their majority-interest partners, then their principal partners, then whichever year produces the least aggregate deferral. Because most individual partners file on the calendar year, most partnerships end up there too.10eCFR. 26 CFR 1.706-1 – Taxable Years of Partner and Partnership
- Personal service corporations, such as medical practices, law firms, and accounting firms, must use the calendar year unless they establish a business purpose.2Office of the Law Revision Counsel. 26 US Code 441 – Period for Computation of Taxable Income
- Taxpayers with no books or no established accounting period default to the calendar year automatically.2Office of the Law Revision Counsel. 26 US Code 441 – Period for Computation of Taxable Income
There’s a narrow exception under Section 444 of the Internal Revenue Code. Partnerships, S corporations, and personal service corporations can elect a fiscal year that differs from the required year by no more than three months.11Office of the Law Revision Counsel. 26 US Code 444 – Election of Taxable Year Other Than Required Taxable Year An S corporation whose required year is December 31 could elect a September 30, October 31, or November 30 year end, nothing earlier. The entity must then make annual “required payments” under Section 7519 to offset the tax deferral the election creates.
Practically, that means a large share of small businesses reading this will find their quarter ends on March 31, June 30, September 30, and December 31 whether they’d prefer a different schedule or not.