Comparison Period for Change Validation 
Definition
The comparison period is a payroll period used in change validation to determine which data has changed since the last export.
Use
The Change Validation function allows the Interface Toolbox to determine which data has changed from one period to another. This data is then transferred to the export file and this determines the volume of data to be exported.
If retroactive accounting is first excluded from individual payroll periods and from multiple exports, then it is easy to determine which data in a payroll period will be used for comparison. A comparison is always made between the data for the current export and the data for the last export, since it identifies the changes that have occurred in the data to be exported.

Data from the March payroll period is compared with the data from the February payroll period when the data is exported. Differences in the March payroll period when compared to the February payroll period are exported.
If data is exported for an employee for the first time, there is no comparison period for payroll. If this is the case, the system exports the data for the existing payroll period.
The determination of payroll periods for retroactive accounting and multiple exports is explained in the following sections.
See also:
Setting the Comparison Period for Multiple Export Setting the Comparison Period for Retroactive Accounting