The combined state and federal capital gains tax rate in California would rise from the current 37.1 percent to 56.7 percent under President Biden’s American Families Plan, according to a new study from the Tax Foundation.

That increase, which would include federal, state and local taxes on financial gains from the sale of assets in California, represented the highest levy among the 50 states, the Tax Foundation’s analysis said.

Nationwide, the combined average capital gains tax rate would amount to an estimated 48.4 percent under the president’s proposal, with the top federal tax rate increasing to 43.4 percent, according to the report. That compares to the current combined average rate of about 29 percent, the study said.

A total of 13 states would have a top combined capital gains tax rate above 50 percent if Biden’s blueprint to help U.S. families with education costs and child care were to become law, according to the Tax Foundation.

Under a foundation tax model, the nation’s gross domestic product would drop 0.1 percent in the long term if the top capital gains tax rate were increased to 39.6 percent. Federal revenue would also decline, the study said, under this scenario.

Combined Capital Gains Taxes Under Biden Families Plan