Build a calendar date from numeric year, month and day parts without parsing locale-ambiguous text. In the English ONLYOFFICE DATE reference, the exact published signature is =DATE(year, month, day). All displayed outputs below are independently calculated expectations, not results observed in an installed ONLYOFFICE editor.

DATE assembles date parts into a date value. It is useful when year, month and day arrive as separate numeric fields, for preparing date columns that can be sorted and used by other date functions, and for preventing regional date-string confusion. The official DATE help documents the order year, month, day and describes the default display as MM/dd/yyyy; you can choose another display format without changing the intended calendar date.

The vendor lists month as 1–12 and day as 1–31. A combination such as February 30 is not a valid Gregorian date; this guide does not promise the engine will normalize or reject it in any particular way. Use verified, valid input rows first, and test overflow or error behaviour natively if your application needs it.

=DATE(year, month, day)

The arguments above are required; the current official reference documents no optional parameters or default argument values for this function. In these formulas, parameter labels such as serial_number describe argument positions; you type a cell reference or numeric expression instead. English examples use commas. All values in the shared exercise are intended to represent unambiguous Gregorian calendar dates. DATE vendor reference.

• ONLYOFFICE Docs / browser editor: vendor help confirms the documented function name and arguments, not reproducibility on every deployed server version. The Docs release history records version 9.4.0 (May 20, 2026), but does not establish that this function first appeared then.
• ONLYOFFICE Desktop Editors: desktop release history is separately maintained; Desktop 9.4.0 is dated May 19, 2026. Do not infer identical support, same error strings, or the introduction version from the shared product branding.
• Android, iOS and other integrations: this investigation does not establish native function support or evaluation parity for a specific app build. Open the function picker in the target editor and perform a local test.
• Formula language and locale: the Advanced Settings documentation describes separate Formula Language and Region controls, including date-display and separator settings. Formulas here use English names, = and commas. If the installed interface expects localized names or a different list separator, adapt and independently validate entry; date cells should be formatted explicitly rather than assumed to display the same across regions.
• 1900 vs. 1904 date system: the same Advanced Settings page documents an optional 1904 date system. It affects date serial calculations and imported workbooks. The tables below compare calendar dates, not hard-coded serial integers. Record the selected date system before comparing workbooks from another spreadsheet product.

Document checks: 2026-10-11 UTC. These are documentation findings, not test logs from a native ONLYOFFICE session.

Create a clean spreadsheet. Type the headings Year, Month, Day, Constructed date, YEAR result, MONTH result, DAY result into A1:G1. Enter the following numbers in A2:C9 (without quotation marks); never paste ambiguous date strings such as 03/04/2026 as input data. Place =DATE(A2,B2,C2) in D2 and fill down to D9. Set D2:D9 to a date format in which the calendar year, month and day are unambiguous—for example yyyy-mm-dd when available. If you see a large integer instead, the date display format probably needs adjusting.

For E2, enter =YEAR(D2); for F2, enter =MONTH(D2); for G2, enter =DAY(D2). Fill all three formulas down through row 9. The shared example-dates.csv in this batch contains the input numbers and independently expected values; the CSV is a test fixture, not an execution transcript. These expected outputs were checked using Python’s Gregorian datetime.date types, which do not simulate ONLYOFFICE’s formula engine or serial-date edge cases.

To reproduce the test without filling, enter each formula from the table below directly into its indicated output cell. Use the worksheet’s actual values, not screenshots or an imagined workbook.

Worked DATE examples

Set A2:C9 to the shared numeric components above. In each D-row, use the matching DATE(Arow,Brow,Crow) formula, then apply a date format such as yyyy-mm-dd. The expected values below are calendar dates, not the exact displayed serial numbers. The leap-year case deliberately uses February 29, 2024, which is a Gregorian leap day.

Advanced example 1: first day of the reporting month

With D4 = 2026-10-11, enter =DATE(YEAR(D4),MONTH(D4),1) in H4 and format as a date. Independently expected: 2026-10-01. This preserves the year and month while selecting a fixed day of 1; it avoids parsing a date string.

Advanced example 2: first day of the calendar quarter

Enter =DATE(YEAR(D4),3*INT((MONTH(D4)-1)/3)+1,1) in H5 and apply the same date format. Expected: 2026-10-01. October belongs to the fourth quarter, whose first month is October (10). The INT and MONTH steps were independently calculated; the combined formula has not been executed in ONLYOFFICE. Check this expression on the user’s actual locale, as separators may vary.

Advanced example 3: a fixed annual reporting boundary

Enter =DATE(YEAR(D4)+1,1,1) in H6: expected 2027-01-01. Use this when defining the start of the next calendar year. It does not by itself define fiscal calendars that begin in other months.

Practical data-quality example

Suppose import fields in A10:C10 contain 2024, 2, 29. =DATE(A10,B10,C10) is expected to represent 2024-02-29, a real leap date. Before importing high-stakes data, validate that values fall in documented argument ranges and the original date actually exists. If a source uses month-first or day-first text, do not guess from the text alone.

• Display versus underlying value: DATE is used in date formulas; format the result as a date before reading it. A cell showing a serial integer is not automatically an incorrect date result.
• No missing-argument default is documented: all three parameters appear mandatory in the official signature; do not omit the day or month.
• Four-digit years: the reference explicitly describes a four-digit year. This guide deliberately avoids two-digit year interpretations and pre-1900 dates.
• Leap years: 2024-02-29 is a valid leap-day check; 2025-02-29 is invalid and intentionally excluded rather than making an unsupported error claim.
• DATE versus DATEVALUE: DATE uses numeric components; DATEVALUE parses date text and can depend on format and localization. These tasks are not interchangeable.

1. The date displays as an integer: ensure the output cell uses a date format. The date serial system is a separate setting from the on-screen formatting. Do not replace an integer with a text date and assume calculations will still work.
2. A formula shows as text: enter it with a leading =, avoid quoted formula strings, and confirm the cell is not forced to text formatting. Use the Insert Function picker to check the installed function name.
3. A copied formula gives unexpected values: compare each reference with the practice table; for example, D4 is the constructed 2026-10-11 date, while A4 is just the year 2026. A YEAR/MONTH/DAY function called on A4 would be interpreting a serial number, not reading the digits “2026” as a year.
4. Dates imported from another locale: 04/05/2026 is ambiguous without regional context. Prefer DATE(2026,5,4) or separately entered numeric parts for a reproducible check.
5. 1900/1904 mismatches: before trusting dates in a migrated Excel file, verify the workbook’s date-system settings. A function name matching in two apps does not prove equality of serial-number handling.
6. Invalid or blank inputs: the short official help pages do not document a complete error-code and type-coercion matrix. Test blanks, negative serials, strings, the year-1900 boundary and localized dates in the target installation; do not claim a specific #VALUE!/#NUM! result without observing it.
7. Unsupported edition or version: check the real product version, Formula Language, platform and installed function picker, then reduce the example to one literal DATE(...) and one extraction. A web documentation page is not a compatibility matrix.

Deliberately unresolved edge cases: the consequences of a day beyond the number of days in a month, month 0 or 13, years before 1900, decimal arguments, and non-Gregorian display calendars are not guaranteed by the short ONLYOFFICE references. The worked examples stay within documented argument ranges and valid Gregorian dates. Do not promote Excel’s normalization behaviour to a verified ONLYOFFICE rule.

Microsoft Excel documents corresponding DATE, YEAR, MONTH and DAY formulas, and Microsoft explains the use of sequential date serials. These are analogous English function names, not proof of matching outcomes for boundary dates, formula-language translations, cross-version imports, or 1900/1904 settings. Excel’s official date-function reference is a useful contrast; ONLYOFFICE Advanced Settings documents the date-system option inside this editor.

In particular, changing a date’s display format is not equivalent to changing the underlying date value. Do not use textual dates for cross-software validation. Export a small workbook and record the versions and chosen date systems in both products if interoperability is important. No comparative application execution was done during this research pass.

• YEAR — official ONLYOFFICE reference (checked 2026-10-11 UTC).
• MONTH — official ONLYOFFICE reference (checked 2026-10-11 UTC).
• DAY — official ONLYOFFICE reference (checked 2026-10-11 UTC).
• DATEVALUE — official ONLYOFFICE reference (checked 2026-10-11 UTC).
• INT — official ONLYOFFICE reference (checked 2026-10-11 UTC).

• ONLYOFFICE Spreadsheet Editor — function documentation
• ONLYOFFICE Insert Functions index
• Docs release history
• Desktop 9.4.0 is dated May 19, 2026
• Advanced Settings documentation
• DATEVALUE
• YEAR — official ONLYOFFICE reference

Verification status: Official documentation checked; example outcomes were independently reasoned or arithmetically checked where applicable. Not executed in ONLYOFFICE Spreadsheet Editor.

• No genuine ONLYOFFICE Spreadsheet Editor screenshots are included; this guide does not use mock application images.