Massachusetts has collected $1.8 billion from its tax on millionaires, which is double the expected $900 million.

The tax imposes an additional 4% charge on any income over $1 million a year and was approved by voters in 2022.

The revenue from the tax is earmarked for transportation and education, including free lunch for every public-school child in the state.

Critics argue the tax will drive high-income earners out of Massachusetts, while proponents claim it will improve public services and infrastructure.

The Tufts University Center for State Policy Analysis found the tax would apply to less than 1% of Massachusetts households in any given year.