Crossmonth

Crossmonth is a term used in calendar design, scheduling, and data analysis to describe an interval, event, or measurement that begins in one calendar month and ends in a different month. It is particularly relevant when durations are not aligned to fixed monthly boundaries, such as tasks that start mid-month or data points that cover partial months.

In user interfaces, crossmonth events are commonly displayed with spanning bars or connectors to indicate the portion of the event in each month. In data processing, crossmonth handling involves distributing or prorating values across the months involved, or treating the event as a multi-month period for aggregation.

Common examples include payroll periods that cross month boundaries, subscription cycles that start mid-month, project tasks that span end-of-month transitions, and temporal metrics like revenue or hours worked that cover parts of adjacent months.

Implementation considerations include accurate calculation of the months spanned, accounting for variable month lengths and leap years, and consistent rules for prorating values. See also: boundary crossing, month boundary, multi-month interval.