THE TAX RELIEF BILL released by legislative leaders on Tuesday significantly changes a law approved by voters in 1986, requiring that excess tax collections be returned in equal amounts to all taxpayers rather than proportional to the taxes they paid.

The so-called tax cap law has been triggered only twice, once in fiscal 1987 and again last year. In 2022, nearly $3 billion was returned to taxpayers, with each one receiving 14 percent of whatever they paid in income taxes. Under the change proposed by the House and accepted by the Senate, the excess tax collections would be divided equally among all taxpayers.

“We want to provide something a little more balanced, a little more equitable across the board,” said Rep. Aaron Michlewitz, the House’s top budget official, at a press conference unveiling the Legislature’s tax relief package.

Sen. Michael Rodrigues of Westport, the Senate’s top budget official, said it is not uncommon for the Legislature to tinker with laws approved by voters.

“Whenever there is legislation passed by referendum, you see oftentimes unintended consequences, that it really hasn’t been thought out to the degree that we can think things out when processing legislation through the normal process,” he said.

Paul Craney of the conservative Massachusetts Fiscal Alliance accused legislative leaders of attempting to hijack the voter-approved law and turn it into “a socialist wealth redistribution scheme.”

It may be a long time before the law is triggered again. In fiscal 2023, tax collections fell $4 billion short of the tax cap threshold.

The tax relief bill also contains a provision requiring married couples to file their state taxes the same way they do their federal taxes. The change is designed to expand the reach of the so-called millionaire tax by capturing couples filing jointly whose combined income exceeds $1 million even though filing individually they would not top the threshold.

The business-backed Massachusetts Taxpayers Foundation opposed the change. It noted, however, that a recent analysis by the Department of Revenue suggested the impact would be limited because more couples would file separately on both their state and federal tax returns.

The Raise Up Massachusetts coalition of unions and community organizations, which led the fight for the millionaire tax, hailed the legislative change as a way to thwart “tax avoidance schemes.” The coalition said the “single-filing loophole” reduces revenue from the millionaire tax by $600 million a year.