Quarterly means once every three months, dividing a year into four equal periods. In a standard calendar year, those four quarters are January through March (Q1), April through June (Q2), July through August through September (Q3), and October through December (Q4). But “quarterly” shows up in several different contexts, from tax payments to business reporting to school schedules, and the exact dates shift depending on which system you’re dealing with.
Standard Calendar Quarters
Most references to “quarterly” follow the standard calendar year breakdown:
- Q1: January, February, March
- Q2: April, May, June
- Q3: July, August, September
- Q4: October, November, December
This is the default meaning when someone says “quarterly” without further context. Quarterly payments, quarterly reviews, and quarterly reports all typically follow this schedule unless a different fiscal year or custom cycle is specified. Each quarter contains roughly 13 weeks, though the exact number of days varies slightly because months aren’t all the same length. Q1 has 90 days (91 in a leap year), Q2 has 91, Q3 has 92, and Q4 has 92.
Quarterly Estimated Tax Payments
If you’re self-employed or earn income that doesn’t have taxes withheld, you’re expected to make quarterly estimated tax payments to the IRS. The word “quarterly” here is a bit misleading because the four payment periods aren’t evenly spaced. For tax year 2026, the federal due dates are:
- 1st payment: April 15, 2026
- 2nd payment: June 15, 2026
- 3rd payment: September 15, 2026
- 4th payment: January 15, 2027
Notice the gap between the first and second payments is only two months, while the gap between the third and fourth is four months. The periods these payments cover don’t line up neatly with calendar quarters either. The first payment covers income earned in January through March, but the second covers just April and May. The third covers June through August, and the fourth covers September through December. If your income is uneven throughout the year, you can use the annualized income installment method (detailed in IRS Publication 505) to adjust each payment based on what you actually earned during that period.
Quarterly Business Reporting
Publicly traded companies are required by the SEC to file a quarterly financial report called a 10-Q after each of the first three quarters of their fiscal year. (The fourth quarter gets covered in the annual 10-K report instead.) The deadline to file depends on the size of the company. Large accelerated filers, those with $700 million or more in public float, and accelerated filers with $75 million to $700 million both get 40 days after the quarter ends. Smaller non-accelerated filers, with less than $75 million in public float, get 45 days.
Not every company’s quarters match the calendar year. Many businesses use a fiscal year that starts in a different month. Retailers, for example, often end their fiscal year on January 31 or early February so the holiday shopping season and its returns fall cleanly within one fiscal year rather than straddling two. In that case, a company’s Q1 might run from February through April. When you see a company report “Q3 earnings,” it’s always worth checking which months that actually covers.
Quarterly in Academic Settings
Some universities use a quarter system instead of semesters. Under this system, the academic year is divided into three 10-week terms (fall, winter, and spring), with an optional summer session. Each term is shorter and more intensive than a traditional 15- to 16-week semester. Schools on the quarter system typically offer more individual courses per year but cover less material in each course, so students take more classes overall to reach the same credit total. If you’re transferring between a quarter-system school and a semester-system school, you’ll generally need to convert credits, since one quarter credit equals roughly two-thirds of a semester credit.
Quarterly Billing and Payments
Outside of taxes and corporate reporting, you’ll run into quarterly billing for things like insurance premiums, property taxes, HOA fees, and some utility services. Paying quarterly means you make four payments per year instead of 12 monthly ones. Some companies offer a small discount for quarterly or annual payment because it reduces their administrative costs, while others charge a convenience fee for breaking an annual bill into smaller chunks. When you sign up for a quarterly payment plan, confirm which months the payments fall in and whether the billing date is the first of the quarter, the 15th, or some other date specific to that company.
In nearly every context, quarterly simply means four times a year at roughly three-month intervals. The specific dates and month groupings vary depending on whether you’re dealing with the IRS, a publicly traded company, a university, or a billing department, so it’s always worth confirming the exact schedule for your situation.