In addition to the provisions of the Act (D.C. Code § 47-2001(p)(2) ), the term "sales price," as used in the Act, shall not include any of the exceptions set forth in this section.
For the purposes of D.C. Code § 47-2001(p)(2)(C), the amount charged for labor or services rendered in installing or applying the property sold shall not be subject to the tax if both of the following conditions are met:
If labor and service charges and sales price are not shown separately, the tax applies to the total amount received from the sale of property and installation charges.
D.C. Mun. Regs. tit. 9, r. 9-407