Installment purchases where interest charge is not separately stated

If personal property or educational services are purchased under a contract—

(A) which provides that payment of part or all of the purchase price is to be made in installments, and

(B) in which carrying charges are separately stated but the interest charge cannot be ascertained,

then the payments made during the taxable year under the contract shall be treated for purposes of this section as if they included interest equal to 6 percent of the average unpaid balance under the contract during the taxable year. For purposes of the preceding sentence, the average unpaid balance is the sum of the unpaid balance outstanding on the first day of each month beginning during the taxable year, divided by 12. For purposes of this paragraph, the term “educational services” means any service (including lodging) which is purchased from an educational organization described in section 170(b)(1)(A)(ii) and which is provided for a student of such organization.

In the case of any contract to which paragraph (1) applies, the amount treated as interest for any taxable year shall not exceed the aggregate carrying charges which are properly attributable to such taxable year.