On or about is used to indicate that a stated date is approximate rather than exact. In legal practice across England and Wales, Scotland, Northern Ireland and Ireland, it commonly appears in contracts, pleadings, indictments and witness statements where the precise date of an event is uncertain, immaterial, or may reasonably vary.The phrase is generally not defined in statute, but its meaning has been clarified through case law and routine usage: it permits a reasonable margin of error around the specified date, provided no prejudice is caused to the other party. In criminal proceedings, “on or about” a given date allows the prosecution some flexibility where exact timing is unclear, while still giving the accused fair notice of the allegation. In civil litigation and transactional documents, it helps avoid technical breach where performance occurs slightly earlier or later than anticipated.Courts in all four jurisdictions interpret “on or about” in a similar, pragmatic way, focussing on context, materiality, and fairness rather than a fixed number of days either side of the stated date.