which pay data must I start collecting now for later use

Remuneration in the broad sense, per employee and per job category

For later reporting, it is advisable to collect data now on total remuneration per employee, not just gross salary. The Directive uses a broad definition of remuneration: in addition to basic salary, it also includes variable and supplementary components, such as bonuses, allowances and other benefits that an employee receives in connection with their employment. If you only keep track of basic salary now, you will miss part of the picture that the reporting requires later.

In addition, it is useful to link remuneration to job categories and to gender, because the reporting focuses on the difference between female and male employees within groups performing equal or equivalent work. Without a classification into job categories, it is difficult to determine afterwards which remunerations are comparable to each other. Which data must be included in a gender pay gap report? goes further into the precise structure of that reporting; here it concerns the data that can already be collected for that purpose. It is also useful to establish whether it is a reporting per location or for the entire organisation, see must I report per location or for the entire organization, because this determines at what level the data will need to be combined later.

Where this follows from: Article 3 and Article 9 of the Directive

Article 3 of Directive (EU) 2023/970 provides the definition of remuneration, and this definition determines which data are relevant to collect. Article 9 of the same Directive describes what the reporting must ultimately contain, including the gender pay gap between female and male employees per category. Dutch implementing rules, about which the Ministry of Social Affairs and Employment publishes information, can elaborate on this further.