Del. Code Ann. tit. 18, § 912
An asset or reduction from liability for the reinsurance ceded by a domestic insurer to an assuming insurer not meeting the requirements of § 911 of this title shall be allowed in an amount not exceeding the liabilities carried by the ceding insurer. The reduction shall be in the amount of funds held by or on behalf of the ceding insurer, including funds held in trust for the ceding insurer, under a reinsurance contract with the assuming insurer as security for the payment of obligations thereunder, if the security is held in the United States subject to withdrawal solely by, and under the exclusive control of, the ceding insurer; or, in the case of a trust, held in a qualified U.S. financial institution, as defined in § 913(b) of this title. This security may be in the form of any of the following:
(3) a. Clean, irrevocable, unconditional letters of credit, issued or confirmed by a qualified U.S. financial institution, as defined in § 913(a) of this title, effective no later than December 31 of the year for which the filing is being made, and in the possession of, or in trust for, the ceding insurer on or before the filing date of its annual statement.
68 Del. Laws, c. 58, § 3; 78 Del. Laws, c. 364, § 3; 83 Del. Laws, c. 104, § 1