The term controlled group has the meaning given to such term by subsection (a) of section 1563, except that more than 50 percent shall be substituted for at least 80 percent each place it appears in such subsection. (II) Controlled groups that include nonincorporated persons Under regulations prescribed by the Secretary, principles similar to the principles of subclause (I) shall apply to a group of persons under common control where one or more of such persons is not a corporation. (2) Containers, packing and transportation charges In determining, for the purposes of this chapter, the price for which an article is sold, there shall not be included any charge for coverings and containers of whatever nature, and any charge incident to placing the article in condition packed ready for shipment. Further, there shall be excluded the amount of tax imposed by this chapter, whether or not stated as a separate charge. A transportation, delivery, insurance, installation, or other charge (not required by the preceding sentence to be included) shall likewise be excluded from the price. (d) Partial payments and installment accounts (1) Partial payments There shall be paid upon each payment with respect to the article a percentage of such payment equal to the rate of tax in effect on the date such payment is due in the case of— (A) a contract for the sale of an article wherein it is provided that the price shall be paid by installments and title to the article sold does not pass until a future date notwithstanding partial payment by installments, (B) a conditional sale, or (C) a chattel mortgage arrangement wherein it is provided that the sales price shall be paid in installments. (2) Sales of installment accounts If installment accounts, with respect to payments on which tax is being computed as provided in paragraph (1), are sold or otherwise disposed of, then paragraph (1) shall not apply with respect to any subsequent payments on such accounts (other than subsequent payments on returned accounts with respect to which