Does the API return the most recent filing date (e.g., last annual report filed)?

Not always. Some states expose filing history, which Cobalt returns in the documents or history fields. Clients can parse these to determine the latest report date. Where available, this may include due dates (e.g., Colorado “Periodic Report Due”) or actual submission dates. Currently, Cobalt normalizes the original formation date (filingDate and normalizedFilingDate); a normalized “last filed date” field is under consideration.

‍