For more than a decade, the report found, the typical net price at private colleges has increased just for higher-income students. But that still doesn’t mean college is affordable for low- or moderate-income families. Students from families with incomes of less than $50,000 are still being asked to pay almost $25,000 to attend a typical private institution, the report found.

“You do not need a Ph.D. to recognize that is not affordable,” Dr. Levine said in an interview.

The net price at public colleges has also become more of a stretch for lower-income families. At public colleges, the typical net price that low-income students pay, adjusted for inflation, rose to $18,000 in 2019-20, from $12,500 in 1995-96.

The gap between public price tags and actual cost deters less affluent students, who don’t even apply once they see an eye-popping list price.

“Sticker shock is a really big issue,” particularly for lower-income, Black and Hispanic students, said James Dean Ward, principal for policy and economic research at Ithaka S+R, a nonprofit research and advisory group focused in part on higher education.

Some colleges are “resetting” tuition to more accurately reflect what students will pay, hoping to attract more applicants. Bridgewater College, a small liberal arts school in rural Virginia, announced last year that it was lowering its published tuition more than 60 percent, to $15,000 from $40,300, starting next fall. (Housing, meals, books, supplies, travel and personal expenses, which add substantially to the cost, are extra.)