Google is being investigated by Ireland's Data Protection watchdog.
The investigation is in relation to how the tech giant processes people's personal data on its online Ad Exchange.
The commission says the statutory inquiry is to make sure it is GDPR-compliant.
"We currently have 54 statutory enquiries open, 19 of those enquiries are into big tech companies but this is the first into Google," said, spokesperson for the Data Protection Commission, Graham Doyle.
"GDPR came in to effect on May 25, 2018, but we became responsible as the lead supervisory authority for Google on January 22 this year."