All bonds or other evidences of debt having a fixed term and rate of interest held by an insurer may, if amply secured and not in default as to principal or interest, be valued as follows:
The Commissioner of Insurance shall have full discretion in determining the method of calculating values according to the rules set forth in this section, but no such method or valuation shall be inconsistent with any applicable valuation or method used by insurers in general, or any such method then currently formulated or approved by the National Association of Insurance Commissioners or its successor organization.
D.C. Mun. Regs. tit. 26, r. 26-A2401