Last Updated on November 25, 2025 by Narendra Sahoo
The NIS2 Directive has raised the bar for cyber resilience across Europe, and one of the biggest changes organizations are trying to wrap their heads around is the NIS2 incident reporting timeline. The timelines are tighter, the expectations are higher, and the penalties for delay or incomplete reporting are far more serious than under NIS1.
If you operate in Europe or serve European clients, understanding how the NIS2 incident reporting requirements work is not optional. It is the difference between being compliant or facing investigations, reputational damage, and potential fines.
What Does NIS2 Consider a Reportable Cyber Incident?
To keep it simple, an incident becomes reportable when it causes or is likely to cause significant disruption, financial loss, safety concerns, or impacts essential or important services.
This could be ransomware, DDoS attacks, unauthorized access, data breaches, or even a supply chain compromise.
This is where many organizations get stuck. They wait for confirmation before reporting. Under NIS2, waiting can put you in violation.
The NIS2 Incident Reporting Timeline Explained
European regulators introduced a multi stage reporting model so authorities get early visibility into serious incidents while giving companies time to investigate.
Here is how the timeline works in real life.
1. Early Warning Within 24 Hours NIS2 Article 23(1)
Companies must submit an early warning within 24 hours of detecting a significant incident.
This is not expected to be a detailed report. It is simply a quick notification to the national CSIRT or competent authority.
What should the early warning include?
- Basic description of the incident
- Whether it is ongoing
- Potential cross border impact (NIS2 Article 23(1)(c))
- Initial assessment of criticality
Think of this as raising your hand early rather than filing a full investigation.
2. Intermediate Report Within 72 Hours NIS2 Article 23(2)
Within 72 hours, companies need to submit a more structured report.
This is where you explain what you know so far and what steps you have taken.
What typically goes in a 72 hour report?
- Confirmed impact
- Affected systems or services
- Technical indicators
- Immediate containment measures
- Whether public disclosure might be required NIS2 Article 23(2)(e)
Most companies struggle here because they do not have proper logging or incident response readiness. If your SOC cannot reconstruct events quickly, you risk sending an incomplete report.
3. Final Report Within One Month NIS2 Article 23(4)
Within one month, organizations are required to submit a detailed final report with lessons learned, root cause analysis, and evidence of remediation.
This stage is where regulators evaluate:
- whether the attack was preventable
- whether controls were adequate
- whether leadership acted responsibly
Companies with weak documentation often face additional scrutiny at this stage.
Practical Impact of the NIS2 Reporting Deadlines
Many organizations underestimate how quickly 24 hours passes when a major cyber incident hits.
Teams are confused, logs are incomplete, communication channels break, and leadership has no clarity. This is exactly why the NIS2 compliance incident reporting rules exist — to push companies toward a more mature incident response culture.
How Companies Should Prepare for NIS2 Incident Reporting
Having helped organizations prepare for EU regulatory cyber frameworks, I can tell you the difference between smooth compliance and panic mode comes down to preparation.
Here is what companies should focus on before an incident happens.
1. Build a Clear Incident Classification System
Not every alert is a reportable incident, but many companies treat them the same.
Define what qualifies as a significant incident under NIS2, including criteria such as:
- service downtime
- financial loss thresholds
- impact on critical functions
- data exposure
- cross border relevance Aligned with NIS2 Article 3 and Article 23(1)
This avoids over reporting and under reporting.
2. Strengthen Your Detect and Respond Capabilities
You cannot report an incident in 24 hours if you detect it after 72.
Invest in:
- centralised logging
- endpoint visibility
- real time alerting
- threat intelligence
- SOC readiness
This is essential for meeting the NIS2 cyber resilience controls requirements. NIS2 Article 21
3. Prepare Templates for Each Reporting Stage
Organizations waste time creating the 24 hour, 72 hour, and 1 month report formats during a crisis.
Create them in advance.
Pre approved templates help teams submit accurate information quickly. (NIS2 Article 23 requirements).
4. Train Executives and Technical Teams
Leadership plays a key role in timely reporting.
Everyone should know:
- when to escalate
- whom to notify
- who takes ownership of reporting
- what communication guidelines apply
This prevents internal delays that could lead to non compliance penalties.
5. Conduct NIS2 Focused Incident Response Drills
Run simulations that follow the NIS2 incident reporting timeline.
This will reveal gaps in:
- communication
- evidence gathering
- forensic readiness
- vendor coordination
- cross border handling (NIS2 Article 23 and Article 24)
Drills also help determine if a situation qualifies for reporting under NIS2 essential and important entities categories.
Common Mistakes Companies Make During NIS2 Reporting
- Waiting for full confirmation before reporting
- Confusing internal severity levels with NIS2 thresholds
- Lack of structured documentation
- Underestimating the scrutiny regulators apply to reports (NIS2 Article 32)
- Missing the one month final report
- Not notifying supply chain partners NIS2 Article 21(2)(d)
These mistakes can lead to penalties or additional audits by authorities.
Final Thoughts
If the NIS2 incident reporting timeline feels complex, our team at VISTA InfoSec is here to make the process easier. We help organisations understand what needs to be reported, prepare the 24 hour and 72 hour submissions, and strengthen their overall NIS2 readiness.
If you want expert guidance or a clearer path to compliance, schedule a call with us. We also support SOC 2, GDPR, ISO 27001, and PCI DSS for companies looking to build a strong and audit ready security program.
Narendra Sahoo (PCI QPA, PCI QSA, PCI SSF ASSESSOR, CISSP, CISA, CRISC, 27001 LA) is the Founder and Director of VISTA InfoSec, a global Information Security Consulting firm, based in the US, Singapore & India. Mr. Sahoo holds more than 25 years of experience in the IT Industry, with expertise in Information Risk Consulting, Assessment, & Compliance services. VISTA InfoSec specializes in Information Security audit, consulting and certification services which include GDPR, HIPAA, CCPA, NESA, MAS-TRM, PCI DSS Compliance & Audit, PCI PIN, SOC2 Compliance & Audit, PDPA, PDPB to name a few. The company has for years (since 2004) worked with organizations across the globe to address the Regulatory and Information Security challenges in their industry. VISTA InfoSec has been instrumental in helping top multinational companies achieve compliance and secure their IT infrastructure.
