periodenstart

Periodenstart is a term used to denote the first day of a defined time period, used for reporting, accounting, billing, or data collection. It marks the point at which the activities, measurements, or revenue recognition for that period begin, and serves as a reference for calculating duration and aggregating data.

It is commonly applied to calendar-based periods such as months, quarters, and years, but many organizations define custom periods aligned to their business needs or contractual terms. In software and data processing, the periode start is used as the baseline for time-based aggregations, filters, and rolling windows.

Determination of the period start can be fixed by policy (for example, the first day of the month) or defined by contractual terms (e.g., billing period starts on the 15th). The period start is usually inclusive, with the period ending just before the next period start. Time zones and calendar rules (such as leap years) can affect exact dates in global operations.

As a key element in financial statements, revenue recognition, and performance metrics, the accuracy of the period start is essential. Related terms include period end, period length, fiscal year, calendar year, and rolling period.