When a policy ends early, the insurer owes back the unearned premium, and Section 481.5 puts a clock on that refund:
Personal lines, such as homeowners: gross unearned premium must be tendered within 25 business days after the insurer receives notice of the event.
Other policies: within 80 business days.
Late amounts bear interest at 10 percent per year.
Ending at expiration instead? For a Section 675 policy, a notice of nonrenewal must be given at least 75 days before expiration (Section 678(c)). A late notice keeps the existing policy in effect, with no change in terms, for 75 days from the date the notice is delivered or mailed.
Do not mix up the numbers: 45 days is the minimum for a renewal offer that reduces limits or coverage (Section 678(a)); 75 days is for a notice of nonrenewal.