24 C.F.R. § 180.510 – Interrogatories.

(a) Any party may serve on any other party written interrogatories to be answered by the party served. If the party served is a public or private corporation, a partnership, an association, or a governmental agency, the interrogatories may be answered by any authorized officer or agent who shall furnish such information as may be available to the party. A party may serve not more than 30 written interrogatories on another party without an order of the ALJ.
(b) Each interrogatory shall be answered separately and fully in writing under oath or affirmation, unless it is objected to, in which event, the reasons for the objection shall be stated in lieu of an answer. The answers shall be signed by the person making them, and the objections may be signed by the attorney or other representative making them. The answers and objections shall be served within 15 days after service of the interrogatories.
(c) It is a sufficient answer to an interrogatory to specify the records from which the answer may be derived or ascertained if:
1. (1) The answer to the interrogatory may be derived or ascertained from the records of the party on whom the interrogatory has been served or from an examination, audit or inspection of such records, or from a compilation, abstract or summary based thereon, and
2. (2) The burden of deriving or ascertaining the answer is substantially the same for the party serving the interrogatory as the party served. The party serving the interrogatory shall be afforded reasonable opportunity to examine, audit or inspect such records and to make copies, compilations, abstracts or summaries. The specification shall include sufficient detail to permit the interrogating party to locate and identify the individual records from which the answer may be ascertained.
(d) Objections to the form of written interrogatories are waived unless served in writing upon the party propounding the interrogatories.