C9 Gender Diversity Ratio: Calculation, Population and Reporting Controls

The formula is simple only after the governance population has been defined.

A ratio can look objective while hiding several judgement choices: which board is the governance body, whether executives or observers are members, how a dual-board structure is treated, what date is used, whether vacancies are counted, and what happens when the male denominator is zero.

The strongest control is a governance-population register reconciled to legal and company-secretarial records. It makes the formula reproducible, allows comparatives to be restated when the population changes, and avoids unnecessary publication of personal information.

Paragraph 64 says that if the undertaking has a governance body in place, it shall disclose the related gender diversity ratio. The current text does not specify a measurement date, whether to use an annual average, how to treat vacancies, how to deal with dual-board structures, or how to present a zero denominator. These are methodology choices that should be documented rather than hidden.

HISTORICAL GUIDANCE / Recommendation (EU) 2025/1710 describes the governance body as the highest decision-making authority and says the ratio is calculated as an average ratio of female to male board members. Its example gives a ratio of 1 where a six-member body has three women and three men. Use this as labelled historical implementation guidance and reconcile it to the final current text.

Under the historical calculation guidance, the ratio is female active members divided by male active members.

FORMULA / Gender diversity ratio = number of female active members of the selected governance body ÷ number of male active members of that body. Example: 3 female members ÷ 3 male members = 1.00, which can be described as a 1:1 female-to-male ratio.

Do not silently convert the result into the percentage of women unless you label it as supplementary information. A body with three women and seven men produces a female-to-male ratio of 0.43, while women represent 30% of the ten-member population. Both figures can be useful, but they answer different questions.

Vacant seats are not people and should not be assigned to the female or male count. They can be disclosed separately because they affect the context: a five-member active board with two vacancies is different from a fully occupied seven-member board. The undertaking should also define when an appointment or resignation becomes effective and whether the ratio is measured at the reporting date or as an average during the period.

METHOD CHOICE / The current C9 text does not clearly prescribe point-in-time versus annual-average measurement. A proportionate first-year approach is to use the reporting date, disclose that convention and apply it consistently. An undertaking using an average should document the weighting and keep member-effective dates. The named technical reviewer should confirm the final method against any updated guidance.

A group-level ratio requires a clear reporting-body decision; subsidiary boards should not be blended without a stated basis.

For a consolidated sustainability report, the body that governs the reporting parent is often the logical C9 population. However, legal structures differ. A holding company may have a supervisory board and management board; a partnership may have a partners’ committee; a cooperative may have an elected board. The methodology should identify the body, legal basis, decision authority and member population. If additional subsidiary-board information is useful, report it as supplementary and do not obscure the C9 ratio.

Comparability depends on using the same body, member definition, measurement date and gender categories from period to period. If the group restructures, changes from reporting-date to average data, or reclassifies a body, the report should explain the change and, where practicable, provide a recalculated comparative. A change in the ratio caused by vacancies should not be presented as a diversity initiative outcome without supporting evidence.

Publish aggregate counts and ratios, not member-level gender data, unless there is a clear lawful and necessary basis.

Do not infer gender from names, photographs, pronouns or external profiles.

Define how self-identification, other/non-binary categories and non-disclosure are treated; the historical female-to-male ratio may not represent every identity.

Restrict the underlying member register to company-secretarial, HR or authorised governance personnel.

Record the lawful-processing basis, retention period and reviewer approval for any personal data used.

ILLUSTRATIVE SCENARIO / A consolidated group has a six-seat supervisory board, with two female members, three male members and one vacancy at 31 December. The management board has four members but reports to the supervisory board. After legal and governance review, the group identifies the supervisory board as its highest governance body. It excludes the vacancy and the management board from the C9 population and reports 2 ÷ 3 = 0.67, together with the counts and one vacancy. The previous-year ratio was 0.50 using the same reporting-date method. It does not claim that the increase resulted from a policy unless it has evidence linking the appointment process to the change.

ADAPT TO FACTS / At 31 December 2026, the Group’s highest governance body was the Supervisory Board. It had five active members: two women and three men; one authorised seat was vacant. Using the female-to-male method described in the methodology note, the gender diversity ratio was 0.67 (2025: 0.50). The Management Board and non-member observers were excluded because they were not part of the selected highest governance body. The ratio is a reporting-date measure. Aggregate counts were reconciled to company-secretarial records and approved by the Corporate Secretary.

MYTH / REALITY / Myth: “C9 is simply the percentage of women on the board.” Reality: the historical Commission guidance describes a female-to-male ratio. The undertaking should define the selected highest governance body, active members and measurement convention, then calculate and label the requested ratio.