Del. Code tit. 30, § 5409

Every document when lodged with, or presented to, any Recorder of Deeds in this State for recording shall set forth therein and as a part of such document the true, full and complete value thereof, or shall be accompanied by an affidavit executed by a responsible person connected with the transaction showing such connection and setting forth the true, full and complete value thereof and the reason, if any, why such document is not subject to tax under this chapter; provided, that in the case of a transaction exempt from tax under § 5401(1)p. of this title, the affidavit shall be made by the grantee.