Two paths across, NIS2 and ISO 27001

Organisations often ask whether to pursue NIS2 compliance on its own or combine it with ISO 27001 certification. The answer depends on your situation, but understanding how they differ can help decision-making.

Key differences in a nutshell

Aspect

ISO 27001

NIS2

Nature

Voluntary international standard for ISMS

Mandatory EU legal requirement

Applicability

Any organisation globally

Essential and important entities in specific EU sectors

Scope

Organisation chooses scope boundaries

Scope determined by law based on sector and size

Flexibility

Risk based control selection from Annex A

Mandatory minimum measures required in Article 21

Certification

Third party certification available

No certification, compliance verified by supervisory authorities

Incident reporting

Internal processes, not mandated

Strict mandatory timelines (24 hours, 72 hours, 1 month)

Penalties

Loss of certification

Legal penalties up to €10M or 2 percent of global turnover

Management liability

No personal liability

Personal liability possible for management bodies

Supply chain

Addressed in controls but flexible

Explicit mandatory requirements

Governance

Required but flexible structure

Board level oversight explicitly mandated

Audit frequency

Annual surveillance and 3 year recertification

Ongoing supervisory oversight and inspections determined by the authority

Why organisations pursue both

Many do, and for good reasons. ISO 27001 provides a proven ISMS framework and methodology, international recognition and market credibility, a structured approach to risk management, third party validation of security programmes, competitive advantage in procurement, and improved customer confidence and trust.

NIS2 adds legal compliance for in scope entities, mandatory incident reporting, explicit supply chain requirements, supervisory oversight and enforcement, sector specific security coordination, and personal accountability for management.

The combined benefits matter. ISO 27001 implementation satisfies many NIS2 requirements. ISO 27001 certification helps demonstrate that you have taken appropriate measures. Shared documentation and evidence reduce duplication. A single ISMS framework covers both. Mature processes reduce the overall compliance burden.

When dual compliance makes sense

Consider pursuing both if market expectations favour it. For example, international customers require ISO 27001 certification, procurement processes reward certified suppliers, competitive advantage existing in the sector, or operating across multiple jurisdictions with differing requirements.

Organisational maturity also plays a role. Dual compliance suits organisations that want structured ISMS guidance, prefer independent validation, value continuous improvement, and have the resources to sustain both programmes.

Risk management benefits may tip the balance as well. Dual compliance supports defence in depth, external validation of controls, structured growth of a security programme, and clear demonstrations of due diligence beyond minimum requirements.

When NIS2 alone suffices

NIS2 compliance alone may be enough if your requirements are narrow. For example, you operate only in EU sectors covered by NIS2, no customer expects ISO 27001 certification, budget constraints are real, or your focus is legal compliance rather than market positioning.

Your existing security programme may already be mature. If you already operate an effective ISMS without certification, and if your controls meet or exceed NIS2 requirements, you may prefer to focus on regulatory obligations rather than external audits.

Organisational priorities might differ as well. Resources may be better spent on improving security rather than managing certification overhead, the certification value may be unclear in your market, you may wish to avoid the audit burden, or you may plan to pursue certification later once compliance is well established.

Integrate efficiently if you pursue both

Share foundations to avoid duplication. A single ISMS framework can serve both requirements. A common risk assessment can feed both programmes. A unified policy structure keeps things consistent. Combined documentation reduces unnecessary paperwork.

Take an incremental approach. First implement the mandatory NIS2 measures for legal compliance. Then expand towards full ISO 27001 Annex A coverage. Pursue ISO 27001 certification once your processes are stable and properly resourced. Maintain both through a unified set of processes going forward.

Map requirements to find overlaps. Article 21 of NIS2 aligns closely with ISO 27001 Annex A. Incident reporting is not part of ISO 27001. Supply chain requirements are similar but phrased more firmly in NIS2. Governance obligations overlap substantially. Use gap analysis to identify what is unique to each.