This notice is to be construed as a Contract Modification Notice within the meaning of Directive 2014/25/ EU (the “Utilities Directive”), and all obligations, requirements, rights and procedures under the Utilities Directive applicable to modifications of a contract during its term shall apply to this notice in full including, but not limited to, Article 89 and Annex XVI. For the avoidance of doubt, this notice shall not have the effect of a Voluntary Ex Ante Notice under the Remedies Directives (Directive 92/13/EEC, as amended by Directive 2007/66 /EC), and should not be relied upon as such. 97.1 Framework Agreements may be modified without a new procurement procedure] (b) for additional works, services or supplies by the original contractor, irrespective of their value, that have become necessary and were not included in the initial procurement where a change of contractor— (i) cannot be made for economic or technical reasons, including requirements of interchangeability or interoperability with existing equipment, software, services or installations procured under the initial procurement, and (ii) would cause significant inconvenience or substantial duplication of costs for the contracting entity; (emphasis added) This exception is indeed applicable for this matter (Microsoft Modification) for the following reasons: • The “additional works/services” from Microsoft are required to ensure continuity of EirGrid Group’s IT estate which include critical services. • The dependency on Microsoft technologies is driven largely by interoperability requirements across core platforms, third party applications, and operational tooling. Many critical business systems—both internally developed and vendor- supplied—are built to run on Microsoft operating systems and leverage Microsoft-native services such as Active Directory, Entra ID, and Windows Server. For example, key providers develop and certify their solutions specifically against Microsoft platforms, meaning that maintaining compatibility requires us to align with the same technology stack. This creates a tightly coupled ecosystem where identity, authentication, networking, and application layers are all designed to interoperate seamlessly within Microsoft frameworks. • As a result, replacing Microsoft technologies is not a simple substitution exercise. Interchangeability is limited because alternative platforms would need to replicate a wide range of integration points across infrastructure, security controls, and application dependencies. Existing architectures show extensive integration between on premises systems and cloud services (e.g. hybrid identity, DNS, security tooling, and monitoring platforms), all of which rely on consistent Microsoft-based protocols and services to function cohesively. Migrating away would therefore require significant redesign of these integrations to ensure continued interoperability between systems, introducing both technical risk and complexity. • In practical terms, any move away from Microsoft would necessitate large-scale re-engineering of business services, replacement or reconfiguration of third-party solutions, and retraining of users and support teams. This would not only introduce substantial cost but also disrupt established operational processes and service delivery. Given the pervasiveness of Microsoft technologies across the EirGrid IT estate, the impact would extend beyond individual systems to the overall coherence of the technology landscape, making transition both technically challenging and operationally disruptive. This Contract Modification Notice captures the renewal contract required until March 2031.

This notice is to be construed as a Contract Modification Notice within the meaning of Directive 2014/25/ EU (the “Utilities Directive”), and all obligations, requirements, rights and procedures under the Utilities Directive applicable to modifications of a contract during its term shall apply to this notice in full including, but not limited to, Article 89 and Annex XVI. For the avoidance of doubt, this notice shall not have the effect of a Voluntary Ex Ante Notice under the Remedies Directives (Directive 92/13/EEC, as amended by Directive 2007/66 /EC), and should not be relied upon as such. 97.1 Framework Agreements may be modified without a new procurement procedure] (b) for additional works, services or supplies by the original contractor, irrespective of their value, that have become necessary and were not included in the initial procurement where a change of contractor— (i) cannot be made for economic or technical reasons, including requirements of interchangeability or interoperability with existing equipment, software, services or installations procured under the initial procurement, and (ii) would cause significant inconvenience or substantial duplication of costs for the contracting entity; (emphasis added) This exception is indeed applicable for this matter (Microsoft Modification) for the following reasons: • The “additional works/services” from Microsoft are required to ensure continuity of EirGrid Group’s IT estate which include critical services. • The dependency on Microsoft technologies is driven largely by interoperability requirements across core platforms, third party applications, and operational tooling. Many critical business systems—both internally developed and vendor- supplied—are built to run on Microsoft operating systems and leverage Microsoft-native services such as Active Directory, Entra ID, and Windows Server. For example, key providers develop and certify their solutions specifically against Microsoft platforms, meaning that maintaining compatibility requires us to align with the same technology stack. This creates a tightly coupled ecosystem where identity, authentication, networking, and application layers are all designed to interoperate seamlessly within Microsoft frameworks. • As a result, replacing Microsoft technologies is not a simple substitution exercise. Interchangeability is limited because alternative platforms would need to replicate a wide range of integration points across infrastructure, security controls, and application dependencies. Existing architectures show extensive integration between on premises systems and cloud services (e.g. hybrid identity, DNS, security tooling, and monitoring platforms), all of which rely on consistent Microsoft-based protocols and services to function cohesively. Migrating away would therefore require significant redesign of these integrations to ensure continued interoperability between systems, introducing both technical risk and complexity. • In practical terms, any move away from Microsoft would necessitate large-scale re-engineering of business services, replacement or reconfiguration of third-party solutions, and retraining of users and support teams. This would not only introduce substantial cost but also disrupt established operational processes and service delivery. Given the pervasiveness of Microsoft technologies across the EirGrid IT estate, the impact would extend beyond individual systems to the overall