Late notice can cost you the cover
Every liability policy requires prompt notice of a claim or an incident likely to produce one. Sitting on a demand letter hoping it resolves is the most common way a household damages its own position. Report it the day it arrives even if you believe it is nonsense, because reporting costs nothing and silence can be treated as prejudice.
The defense is the service you bought
A liability policy appoints and pays for lawyers. That is frequently worth more than the limit itself, because most claims are fought down rather than paid out. Handling it yourself, or admitting anything, undermines the defense before it starts.
Both layers need telling
Where an umbrella sits above a homeowners or auto policy, notice generally belongs to both. The underlying carrier handles it first and the umbrella insurer needs to know it exists, particularly if the demand approaches the underlying limit.