Fiscal year end means the last day of the twelve-month accounting period a business uses to track its finances and file its taxes. Under federal tax law, a fiscal year is any twelve-month period ending on the last day of a month other than December; if it ends on December 31, it’s a calendar year.1Office of the Law Revision Counsel. 26 USC 441 – Period for Computation of Taxable Income So a company with a March 31 fiscal year end runs its books from April 1 through March 31, and its tax returns, financial statements, and internal budgets follow that cycle instead of the calendar.
Fiscal Year vs. Calendar Year
Any business can adopt a calendar year. A fiscal year is the alternative: a twelve-month span that closes on the last day of any other month. The choice is made on your first tax return, and once you file on a calendar-year basis, switching later requires IRS approval.
The IRS also defaults you into a calendar year if you keep no books, have no consistent accounting period, or your current year end doesn’t fall on the last day of a month.2Internal Revenue Service. Tax Years In other words, a fiscal year is something you have to choose and maintain; you don’t drift into one.
Why Businesses Pick a Non-Calendar Year End
The most useful fiscal year end usually falls in a company’s slow season. Closing the books during a lull means fewer transactions to reconcile, lower inventory to count, and less pressure on staff who would otherwise be juggling customers and auditors at once.
Retailers are the standard example. Many end their year on January 31, after the holiday rush and after most returns are processed, so the entire holiday season lands in a single reporting period. Companies that sell heavily to federal or state government customers sometimes align their year end with those clients’ spending cycles, choosing June or September.
The federal government runs on its own fiscal year, October 1 through September 30.3USAGov. The Federal Budget Process
Who Doesn’t Get a Free Choice
The freedom to pick any month-end is real for C corporations and sole proprietors. Pass-through entities face restrictions because the IRS wants to prevent owners from deferring personal income by mismatching the entity’s year with their own.
S Corporations
An S corporation must use a “permitted year”: either a calendar year or another period for which the corporation can show the IRS a legitimate business purpose.4Office of the Law Revision Counsel. 26 USC 1378 – Taxable Year of S Corporation Wanting to delay income to shareholders doesn’t qualify. Most S corporations end up on a calendar year because clearing the business-purpose test requires proving a natural business cycle with specific revenue patterns.
Partnerships
Partnerships follow a cascading rule. The partnership uses the tax year of the partners who together hold more than 50 percent of profits and capital. If no single year meets that test, it uses the tax year shared by all principal partners (those with at least a 5 percent interest). If those partners have different tax years, the partnership defaults to the calendar year or to the year producing the least aggregate deferral of income.5Office of the Law Revision Counsel. 26 USC 706 – Taxable Years of Partner and Partnership Since most individual partners file on a calendar year, most partnerships land on December 31.
The Section 444 Workaround
An S corporation, partnership, or personal service corporation that wants a fiscal year outside the standard rules can make a Section 444 election. This allows a year end with a deferral period of up to three months from the otherwise-required year.6Office of the Law Revision Counsel. 26 USC 444 – Election of Taxable Year Other Than Required Taxable Year An S corporation that would otherwise be locked into December 31 could elect September 30, for instance.
The election comes with a cost. Under Section 7519, the entity must make a yearly required payment to the IRS that approximates the tax owners would have paid without the deferral. The payment is due by April 15 of the calendar year after the election year begins, and failing to make it can terminate the Section 444 election.7Office of the Law Revision Counsel. 26 USC 7519 – Required Payments for Entities Electing Not to Have Required Taxable Year
What Happens When the Fiscal Year Ends
Closing the books is the first task. Accounting reconciles bank accounts, verifies inventory, records adjustments for depreciation and bad debt, and confirms that revenue and expenses fall in the correct period. Those numbers become the starting point for the next year.
Tax Return Deadlines by Entity Type
The federal filing deadline is measured from your fiscal year end, not from April 15:
- C corporations file Form 1120 by the 15th day of the fourth month after year end. A June 30 fiscal year is the exception and files by the 15th day of the third month.8Internal Revenue Service. Publication 509 (2026) – Tax Calendars
- S corporations file Form 1120-S by the 15th day of the third month after year end. Shareholder K-1s go out on the same date.8Internal Revenue Service. Publication 509 (2026) – Tax Calendars
- Partnerships file Form 1065 by the 15th day of the third month after year end.9Internal Revenue Service. Starting or Ending a Business
- Sole proprietors report business income on Schedule C with their Form 1040, due the 15th day of the fourth month after year end (April 15 for calendar-year filers).9Internal Revenue Service. Starting or Ending a Business
Every entity type can request an automatic six-month extension, or seven months for C corporations with a June 30 year end. The extension moves the filing date, not the payment date. Taxes owed are still due at the original deadline, and interest runs on any balance paid late.
SEC Reporting for Public Companies
Publicly traded companies file a Form 10-K annual report with the SEC after each fiscal year end. The deadline depends on the company’s size:
- Large accelerated filers (public float of $700 million or more): 60 days.
- Accelerated filers ($75 million to $700 million): 75 days.
- Smaller reporting companies: 90 days.10eCFR. 17 CFR 240.13a-10 – Transition Reports
A 10-K contains audited financial statements, management’s discussion of results, and risk disclosures. Missing the deadline can bring SEC enforcement actions with civil penalties, and stock exchanges have their own rules that can lead to trading suspensions or delisting when filings run late.
Changing Your Fiscal Year End
Businesses that want to switch year-end dates generally file Form 1128. Some changes get automatic approval under the applicable IRS revenue procedure; others require a formal ruling request. The automatic-approval version is due by the filing deadline (including extensions) for the short-period return the change creates. A ruling request is due by the original due date of the short-period return, without extensions.11Internal Revenue Service. About Form 1128 – Application to Adopt, Change or Retain a Tax Year
The gap between the old year end and the new one becomes a “short tax year,” a period of less than twelve months that requires its own return.12eCFR. 26 CFR 1.443-1 – Returns for Periods of Less Than 12 Months Moving from a December 31 to a September 30 year end, for example, produces a short year running January 1 through September 30, after which the new twelve-month cycle begins October 1. Income for the short period is annualized on the return, which can push the effective rate higher than a full year would.
Public companies changing their fiscal year must also file a Form 8-K disclosing the change and then file a transition report covering the short period, on the same 60/75/90-day tiers that apply to the 10-K. If the transition period is shorter than six months, the company can file the report on Form 10-Q, but audited financials for the gap still have to appear in the first annual report under the new year end.
How to Find a Company’s Fiscal Year End
For any publicly traded company, the fastest source is the SEC’s EDGAR database, which stores every public filing and is free to search.13U.S. Securities and Exchange Commission. Search Filings Search by company name or ticker, open the most recent Form 10-K, and the cover page names the fiscal year end date. EDGAR’s full-text search also lets you filter by form type to pull 10-K and 10-Q filings directly.14SEC.gov. EDGAR Full Text Search
Most public companies also publish annual reports and earnings calendars under an investor relations tab on their websites; the notes to the financial statements spell out the accounting period. For private companies, year-end information sometimes surfaces in state business filings or through commercial credit reporting services, but it isn’t always publicly available.