Cliff Lippard, associate executive director of TACIR, said the study is one in a series of reports on local fiscal flexibility.
"We're not prescribing a solution," he said.
According to the report, families in the lower income bracket had a higher-percentage tax burden than those in the high-income brackets in all the state's counties. The difference was the largest in Williamson County, where 11 percent of poorer families' income goes toward local taxes, compared to 3.4 percent for more affluent families.
Brian Miller, a spokesman for Tennesseans for Fair Taxation, a Knoxville-based group that supports a state income tax, said the current local tax burden "disproportionately hits low-income families."
"We need to seriously revisit our tax structure," he said. "The state can make a lot of revisions that make the state system more fair."