should I include self-employed and flexible workers in workforce data

Count self-employed persons and temporary agency workers separately, do not add to FTE

No, in the VSME core module you do not simply count self-employed persons and temporary agency workers in your own personnel headcount. The headcount and FTE figures that the module requests relate to employees with an employment contract at your enterprise. Self-employed persons are not employees but hired independent contractors, and temporary agency workers are formally on the payroll of the temporary employment agency. They therefore do not belong in the same count as your permanent and fixed-term contracts.

This does not mean your customer does not want to know about it. Many questionnaires have a separate field for "non-own personnel" or explicitly ask about the ratio permanent/flexible, precisely because this says something about labour risks in the chain. If you have not recorded that breakdown separately, the answer is often that you know your own number of employees, but do not regularly register the number of hired workers. That is a valid answer — better than an estimate you cannot substantiate later. The same distinction between "who belongs" and "who does not" also applies to the question on the male-female distribution within the workforcewhere the same definition of "own personnel" applies.

Where this comes from on the basis of the EFRAG VSME core module

The EFRAG VSME core module defines personnel headcount via headcount or FTE, based on employment contracts with the enterprise itself; self-employed persons and temporary agency workers fall outside this because they have no employment contract with the reporting enterprise. Directive (EU) 2022/2464 (CSRD) regulates the reporting obligation for larger enterprises in the chain, but says nothing itself about the precise definition of personnel categories — that is in the VSME module. If a customer specifically asks about working conditions for flexible workers, that also touches on the question of the staff is covered by a collective labour agreementbecause collective bargaining agreement coverage generally applies only to own employees and not to hired personnel.