One of the state’s biggest corporate tax breaks in years could be on its way. So why aren’t more business groups cheering it on and working to get it across the finish line?

We’re talking about “single sales factor apportionment” here. Sure sounds wonky, doesn’t it? Let’s boil it down. It’s a method for deciding how much of a multistate company’s income gets hit by a particular state’s corporate tax. Today, Massachusetts tax collectors use a three-factor system — looking at in-state sales, payroll, and property — to come up with a company’s tax bill. The single-sales switch would limit the factors to one: the amount of a company’s in-state sales.

To put it another way: Big companies with headquarters or other large operations in Massachusetts probably get some relief with single-sales, while out-of-state companies without a huge payroll or campus here might pay more than they do now.

You can probably guess why some of the state’s biggest business groups are steering clear. Some well-known companies that are based here — think State Street, Dunkin’, Tripadvisor, TJX — have pushed for the shift, along with at least two (BNY Mellon, Citizens Bank) headquartered elsewhere but with significant offices here. And some major out-of-state telecoms and banks, Bank of America among them, are not happy about it.

As a result, many of the lobbying and trade groups have members in both camps.

Associated Industries of Massachusetts? Staying neutral. So is the Retailers Association of Massachusetts, where TJX is a member along with big out-of-state players. The Massachusetts Competitive Partnership? Not taking a position. The Massachusetts Taxpayers Foundation hasn’t yet offered up an opinion on the proposal that’s under consideration, and neither has the Massachusetts Bankers Association.

Not every business association is staying out of the fray. The Massachusetts High Technology Council, in a June 21 letter to lawmakers involved in tax talks on Beacon Hill, argued the single-sales shift would make the state a more attractive place for businesses to locate or expand. This state was left behind over the years, Mass. High Tech says, as other states moved to adopt the single-sales approach. Now, more than 35 states currently use single-sales or are scheduled to make the shift, including all of the other Northeast states.

The Massachusetts Business Roundtable seems open to considering the idea — even if there are two out-of-state telcos (AT&T, Comcast) on the membership rolls. JD Chesloff, the group’s president, says single sales “probably needs a fresh look” because Massachusetts has become an outlier.

Stronger support can be found at the Greater Boston Chamber of Commerce, even if Bank of America is among the chamber’s most prominent members. Chamber chief executive Jim Rooney said it would be great if single sales had universal support in the business community — which is lined up together behind reducing the tax on short-term capital gains, another change under consideration at the State House. But Rooney also said he understands why some multistate companies might not embrace a policy that hurts their bottom line.

In February, the Chamber and the Massachusetts Society of CPAs included the single-sales factor and capital gains cut among a slate of tax reforms that the two groups want from Beacon Hill. Then, in April, the House adopted both changes as part of its tax cut plan. But the Senate balked. House and Senate negotiators began meeting last week to resolve those and other differences between the House’s $1.1 billion-a-year tax-cut proposal and the Senate’s more modest $600 million plan.

The two chairs of the conference committee, Representative Aaron Michlewitz and Senator Michael Rodrigues, declined to comment about the single-sales issue, citing State House policy about these kinds of negotiations. What happens in conference committee stays in conference committee.

Amy Pitter, the former state tax commissioner who now leads the CPA association, pointed to several reasons why her group backs the single-sales switch.

Massachusetts is now in a distinct minority of states, she said, putting it at a competitive disadvantage, because companies often make business decisions based on state tax policy. Massachusetts already uses single-sales apportionment for manufacturers, defense contractors, and mutual fund companies — thanks to policies passed by the Legislature in the 1990s aimed at encouraging companies in those sectors to add jobs here. (It didn’t always work out as hoped.) Better, she said, to have a more fair system that applies to all industries in the state, rather than picking winners and losers.

Single-sales is certainly not a slam dunk at this point. In an interview before the Senate released its plan, Senate President Karen Spilka noted that the Senate has heard from some companies that would be hurt by the change. (Spilka has supported the shift in the past, however, and TJX is in her district.)

It’s also not without costs. The House estimates the move would eventually sap $79 million a year in tax revenue; the price tag would go up if exemptions get added in the final version.

Progressives see the expense as an unnecessary giveaway to corporate interests, or worse: a way to game the system. Policy director Phineas Baxandall at the Massachusetts Budget and Policy Center think tank says the single-sales method makes it easier for companies to manipulate their own tax bill, because there are legal ways to change how the location of sales shows up — ways that are simpler to pull off than uprooting employees or changing buildings.

Even though the negotiations only just started, the handicapping has begun. One prevailing theory among lobbyists is that single sales survives the horse trades, but the capital gains cut does not. In addition to the somewhat higher cost of $130 million a year, the capital gains cut is more easily portrayed as a tax break for the wealthy. There has been less noise in that regard around single sales.

Competitiveness remains the most popular buzzword among nearly all local business groups these days. The impact of the millionaires tax is still unknown, six months in, but there’s plenty of data showing an exodus of individuals since 2000 to tax-friendly states such as New Hampshire and Florida in this new era of remote work.

Passing single-sales might be the least the Legislature can do to spur companies to grow here, or to prevent our biggest players from expanding elsewhere. That doesn’t mean everyone in the business community is going to like it.