The adjuster calls, names a policy limit, and offers to tender it. New lawyers hear that number and treat it as the ceiling. It is not the ceiling. It is the first thing the carrier wants you to believe about the case. A single rear-end collision on the 405 can sit on top of a personal auto policy, a business auto policy if the driver was on the clock, an umbrella written by a different carrier, an excess layer above the primary, and your own client's underinsured motorist coverage — plus whatever household policies the resident relatives carry. The money is layered. Your discovery has to be layered too.
Coverage discovery is not a formality you run once and forget. It is the frame that decides whether a catastrophic case gets full value or settles for the first policy an adjuster was willing to name. What follows is how to run it so nothing on the defense side stays hidden.
Start With the Statute That Forces Disclosure
California does not make third-party insurers volunteer their limits before suit. Once you are in litigation, Code of Civil Procedure section 2017.210 changes the math. It entitles a party to discover the existence and contents of any agreement under which an insurance carrier may be liable to satisfy part or all of a judgment, or to indemnify or reimburse for payments made to satisfy it. That language reaches more than the declarations page. It reaches the full policy, endorsements, reservation-of-rights letters bearing on coverage, and the amount and nature of the coverage.
Draft the interrogatory and the request for production to track the statute word for word, then go past it. Ask for every policy of any type that may respond to the loss, primary and excess and umbrella, including policies where the defendant is an additional insured. Ask whether any carrier has denied or reserved rights. Ask for the identity of every carrier and the limits of each layer. A defendant who answers only about the primary policy has given you an incomplete response, and the statute lets you compel the rest.
Map the Tower Before You Value the Case
Think of defense-side coverage as a tower, not a single slab. At the bottom sits the primary policy with its per-occurrence limit and its duty to defend. Above it may sit one or more excess layers that attach only when the primary is exhausted. Above that, an umbrella policy that can drop down to fill gaps the primary never covered at all. Each layer has its own limit, its own attachment point, and often its own carrier with its own lawyer.
You cannot value a serious case until you know how tall the tower is. A driver with a $100,000 auto policy and a $2 million umbrella is a $2.1 million defendant, not a $100,000 defendant. The difference dictates everything downstream: whether you retain a life-care planner, how you build the damages model, how you structure the demand. We have written before about the discipline of separating economic and non-economic damages in a catastrophic demand letter, and that structure only pays off when you have already confirmed there is a tower tall enough to justify the number.
Chase the Employment and Entity Angles
The largest coverage is frequently the one the individual defendant never mentions because it is not his. If the driver was running an errand for work, hauling for an employer, or driving a vehicle titled to a business, a commercial auto or general liability policy may attach through respondeat superior. Those policies carry limits that dwarf personal lines. The named defendant may not even know the policy exists.
Run this down early. Notice the deposition of the person most knowledgeable on insurance and on the defendant's activities at the time of the loss. Ask what the driver was doing, who owned the vehicle, whether any trip sheet or dispatch record exists, and who paid for the fuel and maintenance. In commercial-vehicle cases the paper trail is deep, and the same instincts that drive motions to compel ELD and dispatch records in trucking cases apply to any defendant who might have been working. Follow the employment relationship and you often find the real policy sitting behind it.
Do Not Forget the Coverage on Your Own Side
Some of the most reliable money in an underinsured case comes from your client's own carrier. Insurance Code section 11580.2 governs uninsured and underinsured motorist coverage in California. When the at-fault driver's limits are lower than your client's UIM limits, the UIM coverage fills the gap up to the difference between the two — the underinsured driver's liability limit is credited against the UIM limit, and your client collects the balance.
The mechanics matter and the deadlines are unforgiving. UIM claims run through arbitration, not the tort suit, and the contractual and statutory time limits are shorter than practitioners expect. Confirm your client's own declarations page at intake, not at the end. Identify every policy in the household — a UIM claim can reach the coverage on a resident relative's vehicle if the policy language and the anti-stacking provisions permit it. California enforces anti-stacking clauses, so read the "other insurance" and limit-of-liability language in each policy rather than assuming the limits add together. Whether two household policies combine or one caps the other is a coverage-language question, and it is answered in the endorsements, not in the adjuster's summary.
Watch the Household Exclusions
Resident-relative and household exclusions cut the other way too. A policy may exclude liability coverage for injuries to family members who live in the same house, which can gut a claim where the plaintiff and the driver are related and share an address. Pull the exclusion language before you build the case around that policy. The same document that grants coverage in one paragraph can take it back in the next.
Treat Coverage Coordination as Its Own Workstream
Finding the policies is half the work. The other half is understanding how they interact and who else has a claim on the recovery. When multiple coverages respond to one loss, the order of payment and the offsets between them change what actually reaches your client. This is the same problem, from a different seat, that we cover in coordination of benefits when a client carries two health plans — different layers, one loss, and rules about which pays first.
On the defense side, coordination means knowing whether an excess carrier will contribute to settlement before the primary is formally exhausted, whether an umbrella drops down for an uncovered claim, and whether a reservation of rights signals a coverage fight that will slow any tender. On the lien side, remember that other parties are watching the same recovery: a workers' compensation carrier that paid benefits will assert its statutory claim against the third-party proceeds under the framework we lay out in workers' comp liens in third-party PI recovery. Coverage you find is coverage others may reach, and the net number to your client depends on running both sides of that ledger.
Build the Coverage File at Intake and Keep It Open
The lawyers who never miss a policy treat coverage as a running file, not a single event. At intake, capture your own client's full declarations pages and every household policy. On the defense side, serve the section 2017.210 discovery in the first wave, notice the insurance PMK early, and keep asking as the facts develop, because a defendant's employment status or vehicle ownership can surface a new carrier months in. Diary the UIM deadlines separately from the tort statute so the arbitration clock never runs out while you are focused on the liability suit.
The offer an adjuster names first is a floor the carrier chose for you. Every layer above it — the excess tower, the umbrella, the commercial policy behind the employment relationship, the UIM on your client's own side — exists whether or not anyone tells you about it. Coverage discovery is the work of proving those layers are there before you agree to a number, and the case that gets full value is almost always the one where that work was done first.