D.C. Mun. Regs. tit. 9, r. 9-414
The burden of proving that a sale of tangible personal property or taxable services is not a sale at retail is upon the vendor, unless the vendor timely takes in good faith a certificate from the purchaser that the property is purchased for resale.
As of November 1, 2017, for the purposes of determining sales for resale, the Deputy Chief Financial Officer shall only recognize certificates of resale on forms or copies of forms authorized by the District of Columbia Office of Tax and Revenue. Authorized resale certificates must be obtained through an annual process from the Office of Tax and Revenue at its website mytax.dc.gov.
As of November 1, 2017, an authorized resale certificate shall be valid only for a period of one year and shall include an expiration date. Resale certificates shall be valid only until the expiration date stated on the certificate.
A certificate of resale is only valid if it contains the purchaser's District of Columbia Sales and Use Tax Registration Number.
A purchase is for resale in the following circumstances:
A vendor shall refuse to accept a resale certificate for property and taxable services which he knows or should know is not for resale. Vendors are expected to exercise reasonable judgment in accepting resale certificates in good faith and will not be protected from paying sales tax on the items purchased with resale certificates that are not for resale if they fail to do so.
If all of a person's purchases of tangible personal property or taxable services from a vendor are for resale (fall within any of the circumstances described in Subsection 414.4), the vendor may accept a blanket certificate of resale from the person.
Each certificate of resale shall be maintained by the vendor and shall be authority for the vendor not to add reimbursement for the sales tax to the sales price of the property or service.
Certificates of resale which are canceled in accordance with the provisions of the Act and this chapter are void as of the date of cancellation.
If a person purchases tangible personal property or services for purposes other than those enumerated in the certificate of resale, the person cannot use a certificate of resale to exempt the purchase from the tax. The purchaser must reimburse the vendor for the sales tax or file a return and pay use tax on the purchase.
Any vendor who purchases tangible personal property or services under a certificate of resale, who then gives away such tangible personal property or services for no consideration, will be considered to be the consumer or user of the tangible personal property or services. As such, the retailer must reimburse the vendor for the sales tax or file a return and pay the tax as a consumer or user under the use tax, as the case may be.
D.C. Mun. Regs. tit. 9, r. 9-414