Document with information, hard copy or electronic, related to a completed insurance claim that assists in validating the medical necessity or explains the medical service or procedure (e.g., operative report, discharge summary, invoice). When a claim attachment is included with a paper claim, Block 19 of the CMA-1500 insurance claim form is completed. When a claim is electronically transmitted, practice management and claims software include a data field that indicates that a paper claims attachment is included with the claim. Under the Health Insurance Portability and Accountability Act (HIPAA), electronic standards for claims attachments are being developed. Attachments may be structured (such as Certificates of Medical Necessity) or nonstructured (such as an operative report). Though attachments may be submitted separately, it is common to say the attachment was “submitted with the claim.”