This depends on which debt consolidation solution you choose and which provider. A debt consolidation loan will generally have a loan origination fee that ranges from 1-5% of the amount you borrow. With a consolidation program, there will be a one-time setup/start-up fee, as well as monthly administration fees that are set by the state where you reside.
In both cases, the fees are included with your payments once you consolidate. And you will know about the fees before you consolidate. Just make sure to read your contract agreement carefully.