In tax and financial contexts, quarterly means dividing a 12-month year into four three-month periods, each with its own filing deadlines and payment obligations. The word turns up most often around estimated taxes, employer payroll reporting, and the financial disclosures publicly traded companies file with the SEC. What “quarterly” requires of you depends on which of those situations you’re in.
The Four Calendar Quarters
Most individuals and many businesses operate on a calendar year that runs from January 1 through December 31. That year splits into four equal quarters:
- Q1: January through March
- Q2: April through June
- Q3: July through September
- Q4: October through December
Federal agencies anchor their deadlines to these three-month blocks, which makes it easier to compare financial results across consistent seasonal periods. One quirk: individual estimated tax payments don’t fall neatly at the end of each quarter. They follow a slightly uneven schedule that the section further down lays out.
Fiscal Year Quarters
Not every organization uses the calendar year. A fiscal year is a 12-month accounting period that ends on the last day of any month other than December.1Internal Revenue Service. Tax Years A business whose fiscal year starts on July 1, for example, treats July through September as its first quarter and April through June as its fourth. Some organizations use a 52-to-53-week fiscal year that always ends on the same day of the week rather than the last day of a month.
Whatever the start date, each fiscal quarter still spans three months, and filing deadlines are measured from the end of each quarter rather than from calendar dates. Once an entity adopts a fiscal year, it has to use that period consistently. Changing to a different fiscal year requires filing Form 1128 with the IRS, and depending on whether the change qualifies for automatic approval, the process may involve a user fee and a detailed explanation of business purpose.2Internal Revenue Service. Instructions for Form 1128, Application To Adopt, Change, or Retain a Tax Year
What Quarterly Means for Estimated Taxes
For individuals, “quarterly” most often refers to estimated tax payments. If you earn income the IRS isn’t already withholding from — through self-employment, freelancing, investments, or rental property — you generally have to send in tax four times a year rather than settling up in April. The trigger is expecting to owe $1,000 or more in federal income tax for the year after subtracting your withholding and refundable credits.3Internal Revenue Service. Estimated Taxes This typically covers:
- Self-employed individuals and freelancers, who have no employer withholding taxes from their pay and owe both income tax and self-employment tax.
- Gig workers and independent contractors, including rideshare drivers and people earning income through online platforms, who are treated as self-employed for tax purposes.4Internal Revenue Service. Self-Employed Individuals Tax Center
- Investors and landlords whose interest, dividends, capital gains, or rental income pushes them past the $1,000 threshold when W-2 withholding doesn’t cover it.
- Partners and S corporation shareholders, whose share of business income passes through to their personal return.
If you’re a W-2 employee with no outside income, payroll withholding usually satisfies your obligation and quarterly payments aren’t needed. You can also avoid them by asking your employer to withhold extra using Form W-4.
Self-employment tax rides along with these payments. It funds Social Security and Medicare at a combined 15.3% — 12.4% for Social Security and 2.9% for Medicare. For 2026, the Social Security portion applies to the first $184,500 of net self-employment income; the Medicare portion has no cap.5Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates You have to file a return if your net self-employment earnings reach $400 or more, even if your total income is below the normal filing threshold.4Internal Revenue Service. Self-Employed Individuals Tax Center
Corporations face a lower dollar trigger. They generally must make quarterly estimated payments if they expect to owe $500 or more in tax for the year.6Internal Revenue Service. Underpayment of Estimated Tax by Corporations Penalty
2026 Estimated Tax Due Dates
Individual estimated tax payments for the 2026 tax year are due on these dates:7Internal Revenue Service. 2026 Form 1040-ES, Estimated Tax for Individuals
- 1st payment: April 15, 2026
- 2nd payment: June 15, 2026
- 3rd payment: September 15, 2026
- 4th payment: January 15, 2027
The spacing is uneven. Only two months separate the first and second payments; three months separate the second and third. The fourth payment lands in the following calendar year. You can skip that January payment if you file your full 2026 return and pay the remaining balance by February 1, 2027.7Internal Revenue Service. 2026 Form 1040-ES, Estimated Tax for Individuals When a due date falls on a weekend or legal holiday, the deadline shifts to the next business day.8Internal Revenue Service. Publication 509 (2026), Tax Calendars
Corporate estimated tax installments follow a slightly different pattern: they’re due on the 15th day of the 4th, 6th, 9th, and 12th months of the corporation’s tax year.6Internal Revenue Service. Underpayment of Estimated Tax by Corporations Penalty
What Quarterly Means for Employers
If you have employees, “quarterly” refers to Form 941, the Employer’s Quarterly Federal Tax Return. Each quarter, you report federal income tax withheld from employee paychecks along with both the employer and employee shares of Social Security and Medicare taxes.9Internal Revenue Service. About Form 941, Employer’s Quarterly Federal Tax Return
Form 941 is due by the last day of the month following the end of each quarter: April 30, July 31, October 31, and January 31. If you deposited all employment taxes on time throughout the quarter, you get an extra 10 calendar days to file the return.10Internal Revenue Service. Employment Tax Due Dates
Filing and depositing are separate obligations. How often you deposit withheld taxes depends on payroll size. Employers who reported more than $50,000 in employment taxes during the lookback period deposit on a semiweekly schedule; smaller employers typically deposit monthly.9Internal Revenue Service. About Form 941, Employer’s Quarterly Federal Tax Return Late deposit penalties range from 2% of the unpaid amount for deposits 1 to 5 days late, up to 15% for amounts still unpaid after the IRS issues a notice demanding immediate payment.11Internal Revenue Service. Failure to Deposit Penalty
Most states also require employers to file quarterly wage reports and pay state unemployment insurance taxes, with rates that vary based on your industry, claims history, and the state where your employees work.
What Quarterly Means for Public Companies
Publicly traded companies have a separate quarterly obligation: filing Form 10-Q with the Securities and Exchange Commission after each of the first three fiscal quarters. No 10-Q is required for the fourth quarter, because the annual Form 10-K covers that period.12eCFR. 17 CFR 249.308a – Form 10-Q
Each 10-Q must include unaudited financial statements, a management discussion and analysis of the company’s financial condition and results of operations, disclosures about market risk, and any material changes to risk factors previously reported in the annual 10-K.13U.S. Securities and Exchange Commission. Form 10-Q Large accelerated filers and accelerated filers must file within 40 days after the end of the quarter; all other registrants have 45 days.12eCFR. 17 CFR 249.308a – Form 10-Q
Filings go through EDGAR, the SEC’s Electronic Data Gathering, Analysis, and Retrieval system, which handles documents required under the Securities Exchange Act and makes them publicly available to investors.14U.S. Securities and Exchange Commission. About EDGAR