26 CFR § 48.6416(b)(1)-4 - Supporting evidence required in case of price readjustments.
No credit or refund of an overpayment arising by reason of a price readjustment described in § 48.6416(b)(1)-2 or § 48.6416(b)(1)-3 shall be allowed unless the manufacturer who paid the tax submits a statement, supported by sufficient available evidence -
(a) Describing the circumstances which gave rise to the price readjustment,
(b) Identifying the article in respect of which the price readjustment was allowed,
(c) Showing the price at which the article was sold, the amount of tax paid in respect of the article, and the date on which the tax was paid,
(d) Giving the name and address of the purchaser to whom the article was sold, and