Legislation that would gradually phase out Oklahoma’s tax on work and investment—the personal income tax—continues to move ahead, clearing its first Oklahoma Senate hurdle this week.

House Bill 1539, by state Rep. Mark Lepak and state Sen. Micheal Bergstrom, would cut Oklahoma’s 4.75-percent personal income-tax rate by a quarter point each time that net state revenue increases by at least $300 million, continuing the process until the tax is completely repealed.

State Sen. Julia Kirt, D-Oklahoma City, opposed the bill.

“What we’re doing is hamstringing future legislatures,” Kirt said.

But Bergstrom noted that eight other states have adopted similar “trigger” laws that implement tax cuts when revenue collections increase by a certain amount.

Arizona’s law has resulted in its personal income tax being cut from a 4.5-percent rate to 2.5 percent. Kentucky’s trigger law has cut a half-point off its income tax rate. Missouri’s law has reduced its rate from 6 percent to 4.7 percent today. North Carolina’s trigger law has reduced its tax rate from 5.8 percent to 4.5 percent today.

“Triggers work,” Bergstrom said.

The proposal advanced in Oklahoma at a time when policymakers in Mississippi are celebrating the adoption of a similar plan that will eliminate that state’s income tax over time.

HB 1539 previously passed the Oklahoma House of Representatives on a 76-20 vote. The bill cleared the Senate Revenue and Taxation Committee on a 10-2 vote. It will now proceed to the Senate Appropriations Committee.

Oklahoma’s current 4.75 percent personal income tax rate is among the highest in the region.

Texas has no personal income tax. Colorado imposes a 4.4 percent rate. Officials in Arkansas have cut their rate to 3.9 percent. The top rate in Missouri fell to 4.7 percent in January. Louisiana has cut its income-tax rate to 3 percent.

Among bordering states, only two—Kansas and New Mexico—currently have higher personal income-tax rates than Oklahoma. And officials in Kansas recently voted to gradually cut their tax to 4 percent.

Notably, five states with no personal income tax also have the same or lower effective property tax rates than Oklahoma.