Do you need a CDL to drive a truck under 26000 GVW?

If it's transporting a quantity of hazardous materials which requires placards to be displayed, yes. If it's a bus designed to transport more than 15 persons, yes. If it's attached to a trailer which itself has a GVW of more than 10,000 lbs., yes, UNLESS it falls under the farm truck, emergency vehicle, recreational vehicle, or military vehicle exemptions.

Otherwise, no.