A certificate of insurance is a document the carrier or its insurance broker generates on demand, typically as proof of coverage for a customer or load. It reflects what the carrier or its broker chose to share on the date of issuance. A BMC-91 (or BMC-91X for self-insured carriers, BMC-34 for cargo) filing is a formal federal filing by the underwriter to FMCSA, accepted into the Licensing and Insurance database, that establishes the carrier’s compliance with the financial responsibility requirements in 49 CFR §387.7. A BMC-91 filing is the authoritative federal record; the certificate is the commercial summary. Carrier vetting should pull the BMC filing directly from FMCSA Licensing and Insurance rather than rely on the certificate provided by the carrier. Watch in particular for cancellation notices in the filing history — a string of cancellations suggests something about the underwriter relationship.