ICO Complaint Window

If you complain to a data controller (the organisation holding your personal data) about how it was handled, they should give you a final response. You then have 3 months to refer the matter to the Information Commissioner's Office, which handles complaints under section 165 of the Data Protection Act 2018. The ICO expects complaints to be brought within three months of the organisation's last meaningful response — leave it longer without good reason and the ICO may decline to act.

The calculator adds three calendar months to the final-response date you enter, clamping to the end of shorter months (a response dated 30 November gives a deadline of 28 or 29 February, not a date in March), and sets reminders at 7, 3 and 1 day before the deadline with an .ics download for your calendar.

If the organisation simply fails to respond, you do not have to wait indefinitely: once 3 months have passed since your initial complaint with no meaningful reply, you can take the matter directly to the ICO at that point — enter the date the silence became three months old as a working equivalent.

What this tool does not cover: the three-month window is the ICO's complaint-handling practice, not a court limitation period — it does not affect your separate rights to apply to court for a compliance order (DPA 2018 s.167) or to claim compensation for damage or distress (s.168 and UK GDPR Article 82), which run on ordinary court time limits. The tool does not judge whether your complaint is within the ICO's remit, and it assumes the response you enter really was the organisation's final word — an acknowledgement or holding reply does not start the clock. Keep copies of your complaint and every response to send with the referral.