The government has revised its gender pay gap reporting guidance following the Supreme Court decision in For Women Scotland Ltd v Scottish Ministers.

What has changed?

The guidance now aligns with the legal definition of sex under the Equality Act 2010 confirmed in For Women Scotland Ltd v Scottish Ministers, which treats sex as biological sex.

Two practical changes follow. First, when preparing data, employers must record employees’ sex rather than gender. Second, the calculation guidance has been updated so references now align with sex rather than gender.

The difference matters. ‘Sex’ refers to the biological classification as male or female. ‘Gender’ typically reflects identity, how someone describes themselves. Many organisations have used the two interchangeably. The guidance now draws a clear line.

What does this mean in practice?

If your reporting relies on gender identity data, your figures may no longer align with statutory expectations. That creates two risks. You may misstate your legal position, or you may struggle to explain how your numbers were produced if challenged.

The missing ingredient is consistency. HR systems, diversity surveys, and payroll data often use different definitions. When those datasets feed a single report, inconsistencies surface quickly. That is where you may lose credibility with regulators, employees, and tribunals.

There is also a handling issue. Recording sex for reporting purposes must be tightly controlled. Data about sex, and particularly any Gender Recognition Certificate, is sensitive and you must manage it carefully to avoid both discrimination and data protection risk.

What should you do now?

1. Audit what data you currently use for gender pay gap reporting and how you define it.
2. Confirm that statutory reporting is based on biological sex rather than gender identity.
3. Map where different definitions of sex and gender exist between systems and resolve inconsistencies.
4. Review access to sensitive data and restrict it to those who genuinely need it.
5. Document your data sources, assumptions, and any judgment calls.
6. Ensure board or senior sign-off reflects a clear understanding of the change.

This looks like semantics. It is not. It tests whether your data, decisions, and governance still stand up when the definition shifts.

Source: Preparing your data – GOV.UK