Sweden’s tax authority is pursuing nearly 540 million Swedish kronor, or approximately $56.4 million, in additional taxes from six cryptocurrency mining companies operating in the northern city of Boden, marking a significant escalation in a multi-year enforcement campaign against operators accused of masking their mining activities to claim unwarranted tax benefits.

The reassessments, which stem from a review conducted by Skatteverket, the Swedish Tax Agency, were disclosed in a report by Swedish public broadcaster SVT on September 3. The six Boden-based firms account for the bulk of the latest tax adjustments imposed on crypto businesses, according to the investigation.

Patrik Lillqvist, head of intelligence at Skatteverket, said the…