OpenAI said the decision was "disproportionate" and that the company will file an appeal against it.
The investigation, which started in 2023, also concluded that the U.S.-based company did not have an adequate age verification system in place to prevent children under the age of 13 from being exposed to inappropriate AI-generated content, the authority said.
The Italian watchdog also ordered OpenAI to launch a six-month campaign on Italian media to raise public awareness about how ChatGPT works, particularly as regards to data collection of users and non-users to train algorithms.
Italy’s authority, known as Garante, is one of the European Union’s most proactive regulators in assessing AI platform compliance with the bloc’s data privacy regime.
Last year it briefly banned the use of ChatGPT in Italy over alleged breaches of EU privacy rules.
The service was reactivated after Microsoft-backed (MSFT.O), opens new tab OpenAI addressed issues concerning, among other things, the right of users to refuse consent for the use of personal data to train the algorithms.
"They’ve since recognised our industry-leading approach to protecting privacy in AI, yet this fine is nearly twenty times the revenue we made in Italy during the relevant period," OpenAI said, adding the Garante’s approach "undermines Italy’s AI ambitions".
The regulator said the size of its 15-million-euro fine was calculated taking into account OpenAI’s "cooperative stance", suggesting the fine could have been even bigger.
Under the EU’s General Data Protection Regulation (GDPR) introduced in 2018, any company found to have broken rules faces fines of up to 20 million euros or 4% of its global turnover.
