Seven Democratic senators on the Senate Finance Committee have written to Meta CEO Mark Zuckerberg questioning the company’s use of the federal Research and Experimentation Tax Credit. Meta claimed $6.6 billion in credits from 2023 through 2025 for its extensive buildout of artificial intelligence data centers.

The senators allege Meta improperly classified its AI data centers as experimental “pilot models” to qualify for the credit, which is intended to encourage novel research rather than subsidize the expansion of established infrastructure. They say the claims may violate the “spirit and, potentially, the letter” of the law.

The senators say Meta’s claims could account for more than 10% of all such credits in the United States. They requested answers from Zuckerberg by October 31.