Tools
ICO Breach Notification Deadline Calculator: The 72-Hour Rule
Under UK GDPR you have 72 hours from becoming aware of a personal data breach to report it to the ICO, unless the breach is unlikely to risk people's rights and freedoms. The clock runs on real time, not working hours, so a Friday-evening discovery is due by Monday evening. Enter when you became aware and we will work out the exact deadline and whether you need to report at all.
Work out your ICO reporting deadline
The point you had a reasonable degree of certainty a breach had happened, not when an alert first pinged.
Approximate is fine. The clock runs in real time, including nights and weekends.
This is general guidance on the UK GDPR Article 33 and 34 duties, not legal advice. If in any doubt, report it: the ICO would rather hear about a borderline breach than not. The ICO breach line is 0303 123 1113.
