27 C.F.R. § 45.21
A manufacturer, on specific approval by the appropriate TTB officer as provided in this section, may use an alternate method or procedure in lieu of a method or procedure specifically prescribed in this part. The appropriate TTB officer may approve an alternate method or procedure, subject to stated conditions, when he finds that:
No alternate method or procedure relating to the giving of any bond or to the assessment, payment, or collection of tax, shall be authorized under this section. Where a manufacturer desires to employ an alternate method or procedure, the manufacturer must submit a written application to the appropriate TTB officer. The application shall specifically describe the proposed alternate method or procedure, and shall set forth the reasons therefor. Alternate methods or procedures shall not be employed until the application has been approved by the appropriate TTB officer. The manufacturer shall, during the period of authorization of an alternate method or procedure, comply with the terms of the approved application. Authorization for any alternate method or procedure may be withdrawn whenever in the judgment of the appropriate TTB officer the revenue is jeopardized or the effective administration of this part is hindered. The manufacturer shall retain, as part of his records, any authorization of the appropriate TTB officer under this section for three years following the close of the calendar year in which the operation under such authorization is concluded.
27 C.F.R. §45.21