Northern Ireland is the only part of the United Kingdom without mandatory gender pay gap reporting. Its legislation allows for the introduction not only of gender pay reporting, but also reporting on ethnicity and disability, and requires an action plan to eliminate differences. However the breakdown of the region's devolved government has prevented the introduction of these measures.
Interestingly, Northern Ireland is unusual in having a reversed gender pay gap (i.e., women are on average paid more than men). Read Spotlight on the Gender Pay Gap in the UK for more information on reporting requirements across the UK including for employees in Northern Ireland.