HR_HK_DIFF_BT_2_DATES — Hong Kong Date Difference Function Module

HR_HK_DIFF_BT_2_DATES sits in the Hong Kong country-specific payroll and time evaluation stack (molga 25) inside SAP HCM. Its job is to return the elapsed period between two calendar dates in a form that Hong Kong payroll schemas and personnel calculation rules can use directly, most often for length-of-service based entitlements under the Hong Kong Employment Ordinance: continuous contract testing, severance and long-service payment eligibility, notice period calculation, and pro-rated annual leave. It is not a generically released function module. Like most HR_XX_ prefixed function modules, it ships as an internal building block for the country payroll driver and associated reports rather than as a supported public API, so it carries no release contract and no guarantee that its interface stays unchanged across support packages or releases.

Exact parameter names for this function module are not part of any generally published interface and should be confirmed directly in SE37 before coding against it, since HR_XX_ country function modules are not documented outside the payroll schema context. Based on its naming and typical pattern for this family of date-difference modules, the interface can be expected to include the following roles.

Country-specific HR date modules of this kind typically raise an exception when the two input dates are invalid (not real calendar dates, or blank) and another when the end date falls before the start date, since a negative difference has no meaning for a service-length calculation. If either exception is defined and left unhandled or swallowed with a blanket sy-subrc check that ignores the value, the calling schema or report proceeds with whatever the exporting parameters held before the call, or with initial values, which silently produces a zero or wildly wrong service period. In payroll this is dangerous because a wrong continuous-service duration feeds directly into severance, long-service payment, or leave accrual wage types without any runtime error, so the fault only appears later as a wrong payment or an audit discrepancy, not as a dump.

Call it with both dates already converted to the internal HR date format, never with external DD.MM.YYYY strings, since HR function modules assume the internal representation used across infotypes. Check the return code or exception branch immediately after the call rather than assuming success, and inspect the exporting fields for plausibility, particularly that the returned duration is non-negative and consistent with the input dates, before passing it into any wage type or eligibility check. Because this module is not released, wrap the call in a small local wrapper function so that if the interface changes in a later support package the fix is contained to one place instead of scattered across custom reports and schema rules.

This function module belongs to the on-premise SAP HCM payroll and time evaluation stack and behaves the same whether that stack runs under classic ECC or under S/4HANA with the on-premise HCM component. There is no Fiori app or side-by-side successor for it, and SuccessFactors Employee Central for Hong Kong does not use this on-premise object at all, it applies its own leave and service calculations in the cloud. Because the module is not released, any custom code calling it directly outside a SAP-delivered schema or PCR context should be treated as a clean-core risk item during an S/4HANA move and flagged for review rather than migrated unchanged.

Most incidents involving this module trace back to using it outside the Hong Kong payroll context it was written for.

Ownership sits with the Hong Kong payroll or time management functional consultant who maintains the country-specific schemas and personnel calculation rules, working together with an ABAP developer when the module is called from custom reports rather than standard schemas. This is not a Basis or technical-infrastructure issue; incorrect results point to a schema logic, PCR configuration, or master data sequencing problem in the Hong Kong payroll build.

The module operates within the same Hong Kong country-specific payroll and time schemas that read infotypes such as Actions and Organizational Assignment for the dates it consumes, and its output feeds wage type valuation in the payroll cluster. It sits alongside other generic HR date utilities used for factory calendar and working-day arithmetic, which are used when calendar-day counting rather than statutory continuous-service counting is required.