27 CFR §53.184

1. (a)In general. Any payment of tax imposed by chapter 32 of the Code that is determined to be an overpayment within the meaning of section 6416(b)(2)(A) of the Code and §§ 53.178 and 53.179, by reason of the exportation of any article may be refunded to the exporter or shipper of the article pursuant to section 6416(c) of the Code, if:
   1. (1)The exporter or shipper files a claim for refund of the overpayment, and
   2. (2)The person who paid the tax waives the right to claim credit or refund of the tax.
2. (b)Supporting evidence required. No claim for refund of any overpayment of tax to which this section applies shall be allowed unless the exporter or shipper submits with that claim proof of exportation in the form prescribed by § 53.133, and a statement, signed by the person who paid the tax, showing:
   1. (1)That the person who paid the tax waives the right to claim credit or refund of the tax, and
   2. (2)The amount of tax paid on the sale of the article and the date of payment.