Seattle is the fastest-growing big city across the U.S., but a potential new income tax would sway folks away from the area and negatively affect its bustling business ecosystem.

That’s what Steve Ballmer told KIRO Radio this week, with the former Microsoft CEO noting how an income tax, which is currently moving through city council and would target Seattle’s wealthiest residents, could cause an “unfavorable business climate.”

Ballmer said the income tax would “cause people to think about moving jobs elsewhere” away from Seattle, which he described as “a center of talent in the tech industry.”

Ballmer also opposed a proposed statewide income tax, I-1098, in 2010. He donated $100,000 to the campaign against the initiative, which was ultimately defeated.

The Seattle City Council unanimously approved a motion earlier this month that establishes a timeline to begin consideration of an income tax bill by May 31, with a goal of passing the legislation by July 10. The motion includes few details about what the income tax would look like, but city lawmakers have repeatedly said that it will target Seattle’s wealthiest residents and spare ordinary working people. The law will almost certainly be challenged in court, as Washington state’s constitution forbids local jurisdictions from imposing an income tax.

Seattle currently relies on state and property taxes for its funding. At a recent economic conference, economist Chris Mefford said he believes “it is mathematically impossible to succeed fiscally without a state income tax.”

Madrona Venture Group Managing Director Matt McIlwain countered, saying that tech talent is drawn to the region, partially, because of its lack of income tax. He said the current property and sales tax system is more than adequate to fund the city.

“We have a tax revenue problem, and the problem is what are we going to do with all the incremental tax revenue we have received from our three primary sources,” McIlwain said.

Ballmer, meanwhile, also told KIRO that he has zero intention of moving his NBA team, the LA Clippers, to Seattle. Ballmer, now working on a non-profit called USAFacts, was part of an ownership group that tried to bring the Seattle Supersonics back to Seattle in 2013 before he paid $2 billion to buy the Clippers in 2014.