27 C.F.R. § 479.38
A person shall pay the special (occupational) tax for each location where he engages in any business taxable under 26 U.S.C. 5801 . However, a person paying a special (occupational) tax covering his principal place of business may utilize other locations solely for storage of firearms without incurring special (occupational) tax liability at such locations. A manufacturer, upon the single payment of the appropriate special (occupational) tax, may sell firearms, if such firearms are of his own manufacture, at the place of manufacture and at his principal office or place of business if no such firearms, except samples, are kept at such office or place of business. When a person changes the location of a business for which he has paid the special (occupational) tax, he will be liable for another such tax unless the change is properly registered with the Chief, National Firearms Act Branch for the region in which the special tax stamp was issued, as provided in §479.46.
27 C.F.R. § 479.38