Quarter Calculator

A quarter is a three-month accounting period, and locating a date within one is a matter of integer division. For calendar quarters the month number is divided by three and rounded up, so January through March give Q1 and October through December give Q4. Fiscal quarters use the same division after the month has been rotated by the fiscal year start, which is why the modular expression subtracts the start month, adds twelve to avoid a negative, and takes the remainder before dividing. Calendar quarters are unequal in length: Q1 has 90 days in a common year and 91 in a leap year, Q2 has 91, and Q3 and Q4 each have 92. Fiscal year starts vary by jurisdiction and industry. The United States federal government begins on 1 October, most US states on 1 July and the UK public sector on 1 April, the UK personal tax year on 6 April, and Japanese corporations conventionally on 1 April. Retailers commonly begin around 1 February so the December holiday season closes inside one year. The main limitation of a month-based calculation is that many retailers do not use months at all: the National Retail Federation 4-5-4 calendar builds quarters from thirteen whole weeks, forcing a 53-week year roughly every five or six years in which the fourth quarter runs fourteen weeks. Deadlines anchored to quarter end include Form 10-Q, due within 40 days for large accelerated filers and 45 days for others, and US estimated tax payments falling on or around 15 April, 15 June, 15 September and 15 January.

Dividing the year into four settlement periods long predates corporate accounting. In England the quarter days were Lady Day on 25 March, Midsummer on 24 June, Michaelmas on 29 September and Christmas on 25 December; rents fell due, servants were hired and debts were settled on those dates, and Scotland kept a different set in Candlemas, Whitsunday, Lammas and Martinmas. Because Lady Day opened the English legal year, the quarter structure carried directly into early bookkeeping practice and survives in the vocabulary of the modern fiscal quarter. Quarterly corporate disclosure is a twentieth-century American invention. The New York Stock Exchange began pressing listed companies for interim reports in the early 1900s, and after the Securities Exchange Act of 1934 created the Securities and Exchange Commission the reporting cadence was progressively tightened, with semiannual reporting giving way to a mandatory quarterly Form 10-Q around 1970. The federal fiscal year moved as well: the Congressional Budget and Impoundment Control Act of 1974 shifted the start from 1 July to 1 October beginning with fiscal 1977, on the reasoning that Congress needed three extra months to pass appropriations bills. The retail 4-5-4 calendar was formalized by the National Retail Federation in the mid twentieth century, and the SEC's tiered filing deadlines for accelerated and large accelerated filers were introduced in 2002 and 2003 in the wake of the Sarbanes-Oxley Act.