To determine your company’s fiscal year, start with your entity type: it dictates whether you have real flexibility or are effectively locked into the calendar year. C corporations can pick almost any 12-month period. Sole proprietors are tied to the owner’s calendar year. Partnerships and S corporations default to a required year set by statute and can deviate only by proving a business purpose or making a limited election. Once you know what you’re allowed to use, you either adopt it on your first return or file Form 1128 to change from what you’re using now.
The Three Tax Year Types the IRS Recognizes
A calendar year runs January 1 through December 31. It’s the default for individuals and for any business that keeps no books, has no annual accounting period, or whose accounting period doesn’t qualify as a fiscal year.1Office of the Law Revision Counsel. 26 USC 441 – Period for Computation of Taxable Income
A fiscal year is any 12 consecutive months ending on the last day of a month other than December. A company whose busy season runs through March might pick a June 30 year-end so peak revenue and expenses land inside a single reporting period instead of straddling two.2Internal Revenue Service. Tax Years
A 52-53 week tax year is a fiscal-year variation that always ends on the same day of the week rather than a fixed date. You pick a weekday and one of two anchoring methods: the last time that weekday falls in a chosen calendar month, or the date that weekday falls nearest to the end of a chosen calendar month.1Office of the Law Revision Counsel. 26 USC 441 – Period for Computation of Taxable Income Retailers and manufacturers often prefer this because it produces consistent week-over-week comparisons.
What Your Entity Type Lets You Choose
C Corporations
C corporations have the most latitude. They can adopt any fiscal year-end that suits operations and can generally get automatic IRS approval to change later under Revenue Procedure 2006-45.3IRS.gov. Revenue Procedure 2006-45
Sole Proprietorships
A sole proprietorship isn’t legally separate from its owner, so the business’s tax year must match the owner’s. If your first personal return was filed on a calendar-year basis, the business stays on a calendar year unless the IRS approves a change.2Internal Revenue Service. Tax Years
Partnerships
Section 706 layers the rules. A partnership must use, in this order: the tax year of partners holding more than 50 percent of profits and capital (the majority interest taxable year); the tax year of all principal partners (each holding 5 percent or more) if there’s no majority interest year; or the calendar year if neither test resolves it. Because most partners are individuals on a calendar year, most partnerships land there too. A different year requires establishing a business purpose to the IRS’s satisfaction, and income deferral for the partners is not a valid purpose.4Office of the Law Revision Counsel. 26 USC 706 – Taxable Years of Partner and Partnership
S Corporations
An S corporation must use a “permitted year”: either a December 31 year-end or a year for which it establishes a business purpose.5Office of the Law Revision Counsel. 26 USC 1378 – Taxable Year of S Corporation Deferral to shareholders isn’t a valid purpose, so the calendar year dominates in practice.
The Section 444 Election for Pass-Through Entities
Partnerships, S corporations, and personal service corporations that can’t establish a business purpose still have one route to a non-required year. A Section 444 election lets the entity use a different year, but the deferral period between the elected year-end and the required year-end can’t exceed three months.6Office of the Law Revision Counsel. 26 USC 444 – Election of Taxable Year Other Than Required Taxable Year An S corporation otherwise on a calendar year could elect a September 30 year-end, for example.
The trade-off is a required payment under Section 7519. Partnerships and S corporations that make the election must deposit an amount each year that approximates the tax benefit owners gain from the deferral, calculated as an applicable percentage of the highest individual tax rate (plus one percentage point) applied to the entity’s net base year income. Required payments of $500 or less don’t have to be deposited.7Office of the Law Revision Counsel. 26 USC 7519 – Required Payments for Entities Electing Not to Have Required Taxable Year The payment is refundable when the entity switches back to its required year or terminates the election, so it isn’t a penalty, but it ties up cash every year the election remains in effect.
The election is made on Form 8716, due by the earlier of the 15th day of the fifth month following the month the election year begins, or the due date of the income tax return for the first year of the election.
Proving a Natural Business Year
The most common way to justify a non-calendar fiscal year is the natural business year test in Revenue Procedure 2002-38: at least 25 percent of gross receipts from sales and services must fall in the final two months of the proposed 12-month period, and the entity must meet that threshold for each of the three most recent 12-month periods ending with the proposed year-end.8IRS. Revenue Procedure 2002-38 – Section 5.05 Natural Business Year
A ski resort with heavy February and March revenue might show those months consistently produce 30 percent of annual gross receipts, supporting a March 31 year-end. The test is mechanical. Either the receipts hit 25 percent in all three years or they don’t; arguments about convenience or industry practice won’t substitute for the math.
Entities that pass this test can often get automatic approval to change to that year-end, avoiding the cost and delay of a private letter ruling. Automatic approval is built into Revenue Procedure 2006-45 for corporations and Revenue Procedure 2006-46 for partnerships, S corporations, and personal service corporations.9IRS.gov. Revenue Procedure 2006-46
Adopting or Changing Your Tax Year
Setting a fiscal year at formation is the easy case: file your first return covering the 12-month period you’ve picked, and keep your books on that same basis. Changing an existing tax year requires IRS approval under Section 442.10Office of the Law Revision Counsel. 26 USC 442 – Change of Annual Accounting Period
Automatic Approval
Many changes qualify for automatic approval. Corporations meeting the conditions in Revenue Procedure 2006-45, and partnerships, S corporations, or personal service corporations meeting Revenue Procedure 2006-46, can file Form 1128 (Application to Adopt, Change, or Retain a Tax Year) and proceed.11Internal Revenue Service. About Form 1128, Application to Adopt, Change or Retain a Tax Year Common qualifying moves include shifting to a required tax year, a natural business year, or a 52-53 week year keyed to one of those.
For automatic approval, Form 1128 is due by the due date of the return (including extensions) for the short period created by the change.12Internal Revenue Service. Instructions for Form 1128 There’s no user fee, and the IRS doesn’t issue a formal approval letter. If you hear nothing, the change is approved.
Automatic approval is generally unavailable if the entity is under examination, changed its tax year within the last 48 months (with limited exceptions), or is part of certain tiered structures.
Ruling Requests
If the change doesn’t fit an automatic approval category, file Form 1128 as a private letter ruling request. The deadline is the due date of the return (not including extensions) for the short period.12Internal Revenue Service. Instructions for Form 1128 A user fee applies. For requests received after January 29, 2026, the fee for a letter ruling on a change of accounting period filed on Form 1128 is $6,100.13IRS.gov. Internal Revenue Bulletin 2026-1
The IRS acknowledges receipt within 45 days. If nothing arrives within 90 days, the Form 1128 instructions recommend calling the IRS. Complex requests can take considerably longer.12Internal Revenue Service. Instructions for Form 1128
Have your EIN, current year-end, proposed year-end, and reason for the change ready. If you’re claiming a natural business year, include gross receipts calculations for the three most recent 12-month periods. For a consolidated group, document the parent’s information and the impact on subsidiaries. Review prior returns for conflicting elections before you file.
The Short-Period Return When You Switch
Changing your tax year creates a short period, meaning the gap between the end of the old year and the start of the new one, and you must file a return covering it. The tax cost is often higher than the raw income suggests.
Under Section 443, short-period taxable income is annualized: multiply short-period income by 12, divide by the number of months in the short period, compute the tax on that annualized figure, then take the fraction equal to the short-period months over 12.14Office of the Law Revision Counsel. 26 USC 443 – Returns for a Period of Less Than 12 Months A four-month short period with $100,000 of income annualizes to $300,000, and 4/12 of the tax on $300,000 is usually more than the tax on a straight $100,000 because annualizing pushes income into higher brackets.
Individuals filing a short-period return can’t claim the standard deduction and must itemize. Personal exemptions, to the extent still applicable, are prorated. Credits and limits tied to taxable income use the annualized figure.15eCFR. 26 CFR 1.443-1 Returns for Periods of Less Than 12 Months An alternative calculation under Section 443(b)(2) may reduce the tax if the taxpayer can establish actual income for the full 12-month period beginning on the first day of the short period, but it must be applied for separately after the initial return is filed.14Office of the Law Revision Counsel. 26 USC 443 – Returns for a Period of Less Than 12 Months
Switching Without Approval
Filing on a fiscal year you never got approval for creates lasting problems. The IRS doesn’t treat the new year as valid without prior approval under Section 442, and the assessment window doesn’t run normally. The Internal Revenue Manual states that when a taxpayer incorrectly reports on a fiscal year, the limitations period for a calendar year covered by two such returns doesn’t begin until the second return is filed.16Internal Revenue Service. 25.6.1 Statute of Limitations Processes and Procedures
On examination, the IRS can recompute taxable income for the year of the unauthorized change and every affected year after it, not just the transition year. That can produce recomputed tax, interest running from the original due dates, and accuracy-related penalties. File Form 1128 first, wait for automatic approval or a favorable ruling, and only then file returns on the new basis.