27 C.F.R. § 40.231
A manufacturer of tobacco products may gratuitously furnish tobacco products, without determination and payment of tax, for personal consumption by employees in the factory in such quantities as desired. Each employee may also be gratuitously furnished by the manufacturer, for off-factory personal consumption, not more than 5 large cigars or cigarettes, 20 small cigars or cigarettes, or one retail package of chewing tobacco, snuff, pipe tobacco or roll-your-own tobacco, or a proportionate quantity of each, without determination and payment of tax, on each day the employee is at work. For the purposes of this section, the term "employee" shall mean those persons whose duties require their presence in the factory or whose duties relate to the manufacture, distribution, or sale of tobacco products and who receive compensation from the manufacturer, or a parent, subsidiary, or auxiliary company or corporation of the manufacturer. Such product furnished for off-factory consumption shall be furnished to the employee within the factory and taken from the factory by the employee on the day for which furnished. Employees shall not sell, offer for sale, or give away products so furnished.
27 C.F.R. § 40.231