Each interrogatory shall be answered separately and fully in writing under oath, unless it is objected to, in which event the reasons for objections shall be stated in lieu of an answer. The answers are to be signed by the person making them, and the objections signed by the attorney making them.
The party upon whom the interrogatories have been served may object to the failure to follow the Format requirements in subpart (B) by returning the interrogatories to the party who caused them to be served. If this objection is to be made, the interrogatories shall be returned to the party who caused them to be served not later than the seventh (7th) day after they were received. If the interrogatories are not returned in that time, then this objection is waived.
An interrogatory otherwise proper is not objectionable merely because an answer to the interrogatory involves an opinion, contention, or legal conclusion, but the court may order that such an interrogatory be answered at a later time, or after designated discovery has been completed, or at a pre-trial conference.
Ind. R. Civ. P. 33