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EDATE in Collabora Office Calc: Move Dates by Calendar Months

Date & Time Intermediate Collabora Office Calc

Use Collabora EDATE with signed month offsets, a documented short-month example and anchored schedules that keep calendar rules explicit.

Verification status: See the evidence and test scope described in this guide. How formula examples are checked

Quick answer: EDATE(start_date;months) returns a date a specified number of calendar months from a starting date. With a 15 October 2026 anchor, an offset of three has independently expected date 15 January 2027. A month shift is different from adding a fixed number of days.

Availability and version history

  • Introduced: original Collabora release and launch date are not established by the sources reviewed.
  • Availability: documented in Collabora Office 26.04 help, scoped to that desktop-help release.
  • Platform scope: separately deployed Online and mobile versions are not inferred from desktop documentation.
  • Checked: October 14, 2026. Direct documentation and independent calendar/time controls; no native Collabora test was performed.

Syntax and documented scope

=EDATE(start_date;months)

Both arguments are required. The Collabora reference defines negative offsets as earlier months and positive offsets as later months. These examples use integer month offsets and actual date values, avoiding an unverified fractional-offset rule.

Use English function names and semicolon separators in these controls. Format EDATE outputs as dates; the underlying result is numeric, rather than a text label with a fixed visual layout.

Example 1: move forward and backward from one anchor

=EDATE(DATE(2026;10;15);3)
=EDATE(DATE(2026;10;15);-2)
=EDATE(DATE(2026;10;15);0)

Expected dates are 15 January 2027, 15 August 2026, and 15 October 2026. The year boundary is handled as part of the calendar-month calculation.

The fifteenth day exists in every target month used here. These ordinary controls establish the intended month offset without relying on a rule for a missing day such as February 31.

Example 2: compare one month with thirty days

=EDATE(DATE(2026;10;15);1)
=DATE(2026;10;15)+30

Expected dates are 15 November 2026 and 14 November 2026. There are 31 days between these corresponding mid-month dates, so thirty days does not implement the same schedule.

A calendar-month rule and a fixed-day rule may agree for some anchors and disagree for others. Choose the rule before selecting the formula, rather than treating the difference as a spreadsheet error.

Example 3: inspect the source’s short-month control

The direct 26.04 reference demonstrates one month before 31 March 2001:

=EDATE(DATE(2001;3;31);-1)

Expected date: 28 February 2001. The source’s equivalent ISO-text example reports serial 36950 under the default 1899-12-30 date base.

February 2001 does not contain a thirty-first day. This directly documented example establishes that particular short-month outcome; it does not establish every invalid-date, fractional-month or timestamp rule. The calendar date is more portable than treating serial 36950 as meaningful under every date base.

Advanced example: generate a schedule from a fixed anchor

Put =DATE(2026;10;15) in A2 and offsets −3, −1, 0, 1, 3 and 12 in B2:B7. In C2 enter and fill down:

=EDATE($A$2;B2)

Expected dates are 15 July 2026, 15 September 2026, 15 October 2026, 15 November 2026, 15 January 2027 and 15 October 2027. The fixed anchor remains A2; each row’s offset is measured from it.

Using the previous result as the next anchor instead accumulates shifts. Applying one month and then three months to the October 15 anchor reaches 15 February 2027, four months after the original, rather than January 15.

Advanced check: month-end and anniversary rules differ

=EDATE(DATE(2026;10;15);3)
=EOMONTH(DATE(2026;10;15);3)

Expected dates are 15 January 2027 and 31 January 2027. EOMONTH explicitly chooses the target month’s last date. EDATE does not mean that every returned date is a month end.

Neither formula adjusts for holidays or guarantees a working-day result. Apply a separately documented work-calendar rule if the schedule requires that additional constraint.

Preserve the original anchor and evidence limits

The documented March 31-to-February 28 control shows why a calendar shift can lose the original day number. Returning to March from a stored February 28 value cannot recover information that was discarded. Keep the requested anchor separately when a repeating schedule depends on it.

The source recommends DATE or quoted ISO 8601 text rather than ambiguous slash-separated date strings. Exact invalid-input errors, every short-month composition, fractional offsets and time-fraction behavior remain unverified here. These are independent calendar expectations, not native Collabora outputs.

References and verification

The dedicated product help was read directly. Calendar and numeric outputs are independently calculated expectations, with stated parsing and boundary limits. No native runtime or universal cross-deployment certification is claimed.