### Question
How is the "piggyback trailers or semitrailers" defined?


### Answer
The term **piggyback trailers or semitrailers** is defined in *26 U.S.C. § 4051* as follows -

> any trailer or semitrailer—


(A) which is designed for use principally in connection with trailer-on-flatcar service by rail, and


(B)(i) both the seller and the purchaser of which are registered in a manner similar to registration under section 4222, and


(ii) with respect to which the purchaser certifies (at such time and in such form and manner as the Secretary prescribes by regulations) to the seller that such trailer or semitrailer—


(I) will be used, or resold for use, principally in connection with such service, or


(II) will be incorporated into an article which will be so used or resold

#### Citation:
  - *26 U.S.C. § 4051*
  - Heading: **Subtitle D-Miscellaneous Excise Taxes > CHAPTER 31-RETAIL EXCISE TAXES > Subchapter C-Heavy Trucks and Trailers**

