In 2009, Insurance Law §3420 was amended to bring New York into accord with most states by introducing a prejudice standard when insurers deny coverage based on late notice in death and bodily injury liability claims. Since then, late notice disclaimers by insurers to named insureds have largely sunset.

However, as reflected by the numerous reported appellate cases, disputes involving late notice in the additional insured (AI) context remain robust.

Despite a relatively developed body of case law, parties seeking guidance on the numerous timeframes typically involved in late notice and late disclaimer situations may be surprised to find gaps in authority and unexpected ramifications.