“The core of it, like we’re the ultrarich—that just sticks in my craw,” said Geoff Thompson, of New York’s Westchester County, who runs a marketing firm with his wife, earning together between $300,000 and $350,000 a year. “I don’t know what it’s like in that rarefied atmosphere where people are making multiple millions.”

Mr. Thompson’s household is one of nearly five million that earn between $200,000 and $500,000 annually. They make up the largest subset of the top 2% of earners. Fewer than 1.2 million households earn more than $500,000…

If Congress fails to reach a deal and tax increases automatically kick in, high-earning families with income up to $500,000 will see their tax bill jump by about $14,650 on average, according to the Tax Policy Center, a joint venture of the Urban Institute and the Brookings Institution…

Mr. Thompson, 65 years old, said a rising tax tab means he would cut back on spending so he and his wife can continue saving for retirement.