Del. Code tit. 18 § 3521
A group health insurance policy shall contain a provision that the insurer will furnish to the person making claim, or to the policyholder for delivery to such person, such forms as are usually furnished by it for filing proof of loss. If such forms are not furnished before the expiration of 15 days after the insurer receives notice of any claim under the policy, the person making such claim shall be deemed to have complied with the requirements of the policy as to proof of loss upon submitting, within the time fixed in the policy for filing proof of loss, written proof covering the occurrence, character and extent of the loss for which claim is made.
The nonhospital claim form to be used under this provision is the Health Care Financing Administration Form-1500 or its successor. This form requirement shall not apply to medical payments made by the federal government, prescription drug claims, dental claims or claims using an electronic paperless submission process.
18 Del. C. § 3521