42 CFR §414.232

1. (a)General payment rule. Except as provided in paragraph (b) of this section, payment for TENS is made on a purchase basis with the purchase price determined using the methodology for purchase of inexpensive or routinely purchased items as described in § 414.220. The payment amount for TENS computed under § 414.220(c)(2) is reduced according to the following formula:
   1. (1)Effective April 1, 1990—the original payment amount is reduced by 15 percent.
   2. (2)Effective January 1, 1991—the reduced payment amount in paragraph (a)(1) is reduced by 15 percent.
   3. (3)Effective January 1, 1994—the reduced payment amount in paragraph (a)(1) is reduced by 45 percent.
2. (b)Exception. In order to permit an attending physician time to determine whether the purchase of the TENS is medically appropriate for a particular patient, two months of rental payments may be made in addition to the purchase price. The rental payments are equal to 10 percent of the purchase price.