SARASOTA COUNTY — A proposed state constitutional amendment on property-tax exemptions could cost the county millions of dollars in lost revenue, according to county commissioners.

The commission this week focused on the potential financial consequences of Amendment 4, which would put a 5 percent cap on annual changes in assessments of nonhomestead property, instead of a 10 percent cap. Amendment 4 also provides first-time homebuyers with an additional tax exemption equal to 50 percent of the value of the property.