(a) Tax—(1) Tax not part of taxable sale price. The tax imposed by chapter 32 of the Code on the sale of an article is not part of the taxable sale price of the article. Thus, if a manufacturer computes the tax on a sale price which is determined without regard to the tax, and it charges the proper tax as a separate item, the amount of tax so charged does not become a part of the taxable sale price and no tax is due on the tax so charged. Where no separate charge is made as tax, it will be presumed that the price charged to the purchaser for the article includes the proper tax, and the proper percentage of such price will be allocated to the tax.

(2) Computation of tax. If an article subject to tax at the rate of 10 percent is sold for $100 and an additional item of $10 is billed as tax, $100 is the taxable selling price and $10 is the amount of tax due thereon. However, if the article is sold for $100 with no separate billing or indication of the amount of the tax, it will be presumed that the tax is included in the $100, and a computation will be necessary to determine what portion of the total amount represents the sale price of the article and what portion represents the tax. The computation is as follows:

$$ Thus, if the tax rate is 10 percent and the sale price including tax is $100, the taxable sale price is $90.91 (that is, $100 divided by (100+10)), and the tax is 10 percent of $90.91, or $9.09.

(b) Transportation, delivery, insurance, or installation charges—(1) Charges incurred pursuant to sale. Charges for transportation, delivery, insurance, installation, and other expenses actually incurred in connection with the delivery of an article to a purchaser pursuant to a bona fide sale shall be excluded from the sale price in computing the tax. Such charges include all items of transportation, delivery, insurance, installation, and similar expense incurred after shipment to a customer begins, in response to the customer's order, pursuant to a bona fide sale. However, costs of such nature incurred by a manufacturer, producer, or importer in transporting, in the normal course of business and for its benefit and convenience, articles from a factory or port of entry to a warehouse or other facility (regardless of the location of such warehouse or facility) are not considered as being incurred in connection with the delivery of an article to a purchaser pursuant to a bona fide sale, and charges therefor cannot be excluded from the sale price in computing tax liability. Similarly, an allowance granted by a manufacturer as reimbursement for expenses incurred by the purchaser in shipping used articles to the manufacturer for credit against the purchase price of taxable articles shall not be excluded from the sale price when computing tax due on the sale of the taxable articles. In any event, no charge may be excluded from the sale price unless the conditions set forth in paragraph (b)(2) of this section are complied with. Said conditions are prescribed under the authority granted the Secretary in section 4216(a) of the Code.

(2) Only actual expenses to be excluded. Where a separate charge is made for transportation or other expenses incurred in connection with the delivery of an article to the purchaser pursuant to a bona fide sale, there shall be excluded in arriving at the sale price subject to tax only that portion of the charge which represents the actual expenses incurred for the transportation or other excludable expenses. Where a separate charge is less than the actual expense, the difference is presumed to be included in the billed price. Such difference, together with the separate charge, shall be excluded in arriving at the sale price on which the tax is computed. Similarly, where no separate charge is made but the manufacturer, producer, or importer incurs an expense of the type to which this paragraph has application, the amount of such expense actually incurred shall be excluded from the sale price on which the tax is computed. Where transportation expense is incurred in conjunction with a shipment composed of both taxable and nontaxable articles, only the portion of the expense allocable to the taxable articles shall be excludable. In general, unless the taxpayer establishes to the satisfaction of the appropriate TTB officer that another method reasonably apportions such freight expense between taxable and nontaxable articles, such expense should be apportioned on the basis of the relative weights (or, if available, the relative published tariff rates) applicable to the taxable and nontaxable articles. Where it is not feasible to apportion such expense on the basis of relative weights or tariff rates, the expense shall be apportioned on another reasonable basis; for example, in the case of a shipment including both taxable and nontaxable articles which are subject to the same tariff rate, it may be appropriate to apportion the transportation expense on the basis of the relative sale prices. A charge for insurance in connection with the delivery of an article to a purchaser is considered to represent an expense actually incurred only to the extent that an amount equivalent to such charge is paid or payable by the manufacturer to a person authorized to assume such insurance risk.

(3) Transportation, delivery, or installation services performed by manufacturer. For purposes of computing the taxable sale price of articles, it is immaterial whether the transportation, delivery, or other services of the type to which this paragraph has application are performed by a common carrier or independent agency for or on behalf of the manufacturer, producer, or importer, or are performed by the manufacturer, producer, or importer with the use of its own vehicles or other facilities. Thus, where a manufacturer, producer, or importer performs the transportation, delivery, or other services with its equipment, tools, employees, etc., the cost of such services allocable to the sale of the taxable article shall be excluded. In determining whether an expense is an excludable transportation or delivery expense, only those expenses incurred by reason of the fact that the purchaser accepts delivery at some point other than the manufacturer's place of business shall be considered excludable transportation or delivery expenses. All expenses incurred in placing an article packed, ready for shipment on the loading dock at the manufacturer's factory are not excludable transportation or delivery expenses. An allowance granted by the manufacturer, producer, or importer to the purchaser for transportation, delivery, or other expenses incurred or to be incurred by the purchaser in connection with the sale shall be excluded in computing the taxable sale price, if charges for similar expenses would be excludable if incurred by the manufacturer.

(4) Records in support of exclusion. Every manufacturer, producer, or importer making sales of taxable articles shall keep records which will disclose the amount of transportation, delivery, insurance, installation or other expense actually incurred by it in connection with the delivery of a taxable article to a purchaser pursuant to a bona fide sale.

(c) Other charges. A charge or expense not within the scope of paragraph (a) or (b) of this section, whether or not separately stated, may not be excluded in computing the taxable sale price unless it can be shown by adequate records that the charge or expense is not properly included as a manufacturing or selling expense or is in no way incidental to placing the article in condition packed ready for shipment. Commissions to manufacturers' agents, or allowances, payments, or adjustments made to, and for the benefit of, persons other than the purchaser may not be excluded or deducted, under any condition, in computing the sale price upon which the tax is computed.