Revise insurance premium taxes for certain captive insurers

This bill updates Montana's tax rules for captive insurers and special purpose insurers, which are insurance companies owned by businesses or individuals to cover their own risks. It establishes a tiered premium tax structure where direct premiums are taxed at 0.4% on the first $20 million and 0.3% thereafter, while assumed reinsurance premiums face lower rates ranging from 0.225% to 0.050% depending on the amount. The legislation also sets a minimum annual tax of $5,000 for most captive insurers, prorated based on when they are authorized or surrender their authority, and groups companies under common ownership and control into a single taxable entity. These changes apply to tax years beginning after December 31, 2025.