Time & Dates

What Is a Calendar Quarter?

A calendar quarter is one of four three-month periods of the year: Q1 is January to March, Q2 is April to June, Q3 is July to September, and Q4 is October to December. Businesses use quarters for financial reporting, and some tax payments are organized around quarters.

Fiscal Quarters

Organizations with a fiscal year that does not start in January number their quarters from the start of their fiscal year instead.

Quarterly Taxes

US estimated tax deadlines are roughly quarterly but do not match calendar quarters exactly.

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🔗 Related Terms

Fiscal Year Estimated Taxes ISO Week Number

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Last updated: September 29, 2026. This definition is for general educational purposes only. It is not financial, investment, tax, legal, or medical advice, and it does not recommend any product or course of action. For decisions about your own situation, consult a qualified professional.