Cellulosic Biofuel Not Used as Fuel(p13)

If the cellulosic biofuel producer credit was claimed, you are liable for an excise tax if the cellulosic biofuel is not used or sold for use in a trade or business, used or sold for use in the production of a qualified cellulosic biofuel mixture, or sold at retail and placed in the fuel tank of the purchaser.

Report the tax on Form 720. The rate of tax depends on the applicable rate used to figure the credit. No deposits are required.