A certificate of insurance is not evidence of coverage, and it says so on the form

Read the paragraph at the top of any ACORD 25. It tells you the certificate is issued as a matter of information only, confers no rights on the certificate holder, and does not amend, extend, or alter the coverage afforded by the policies.

The form your entire compliance program is built on states that it proves nothing. That is worth understanding rather than working around, because it changes what you should be collecting.

What the certificate is for

A certificate is a summary produced by an agent, describing policies that exist somewhere else. It is a convenience document. It tells you what to expect and it creates no obligation on the carrier.

Three consequences follow.

An error on a certificate generally does not create coverage. If the agent typed $2,000,000 and the policy says $1,000,000, the policy governs. Courts have occasionally found agent liability for a negligent misrepresentation, which is a claim against the agent rather than coverage under the policy, and it is a poor substitute.

A certificate is accurate as of its issue date and says nothing about tomorrow. A policy cancelled the day after issuance leaves you holding a valid-looking document describing coverage that no longer exists.

Language in the description box does not amend the policy. This is the one that matters most in practice.

The endorsement is the document that changes the policy

An endorsement is part of the contract. It amends the policy, is signed off by the carrier, and creates rights.

For the three things property managers ask for, the endorsement is what proves them:

Additional insured status comes from an endorsement in the CG 20 family. CG 20 10 covers ongoing operations, CG 20 37 covers completed operations, and a vendor who provides only the first has no coverage for you after they leave the site. That distinction alone justifies asking for the form.

Waiver of subrogation comes from its own endorsement, separately on each policy it needs to apply to. General liability and workers compensation are different policies and need different waivers.

Primary and non-contributory treatment comes from either a specific endorsement or from language inside the additional insured endorsement. Without it, the vendor's carrier can argue your policy shares the loss pro rata, which turns a clean tender into a coverage dispute between carriers with you in the middle.

Blanket endorsements are why this is workable at scale

If every vendor needed a scheduled endorsement naming your entity, vendor onboarding would take weeks and brokers would charge for each one.

Blanket additional insured endorsements solve that. They extend status automatically to any party the named insured has agreed in a written contract to add, without listing anyone. Most commercial general liability programs carry one.

Two things to check when a vendor relies on a blanket form.

The trigger. Blanket forms typically require a written contract executed before the loss. An oral agreement or a purchase order with no insurance provision may not trigger it, which means your own contracting discipline is part of your coverage.

Whether it reaches completed operations. Many blanket forms cover ongoing operations only, which means the coverage ends when the job does, and pollution and construction defect claims surface long after that.

Getting the blanket endorsement form once per vendor, rather than a scheduled endorsement per property, is the practical middle ground. One document, read once, applies portfolio-wide.

The cancellation notice provision is mostly gone and the form admits it

Older certificates carried language promising 30 days notice of cancellation to the certificate holder. Current ACORD forms say notice will be delivered in accordance with the policy provisions, which for most policies means notice to the named insured and to nobody else.

So the practical position is that you will not be told when a vendor's policy cancels. You will find out at renewal, or when you check, or after a claim.

That is the entire argument for expiration tracking with automated vendor reminders ahead of the date, which is what IDCore does. Preventing the lapse is the reachable goal; a document reader cannot know that a policy cancelled yesterday, and any vendor telling you theirs eliminates mid-term cancellation risk is describing something certificate reading cannot do.

Two tiers, split by how much a claim would cost

Requiring endorsement copies from every vendor is a real friction cost and it will slow onboarding on work that does not need it.

A defensible split:

For low-risk trades, accept the certificate with description-box language, track expiration, and require a signed agreement with the insurance provisions in it. The contract is what makes the blanket endorsement bite.

For high-risk trades and for any vendor whose work could produce a large claim, require the additional insured endorsement form, the waiver of subrogation endorsement, and confirmation that completed operations is included.

That is maybe 15% of your vendor base carrying the additional friction, covering most of the exposure.

Ask one vendor for the form

Pick the vendor doing your highest-risk work. Ask for a copy of the additional insured endorsement, not the certificate.

Two things to notice: how long it takes, and whether the form is CG 20 10 or CG 20 37.

If it is 20 10 only, you have no coverage for that vendor's completed work, and the certificate on file did not tell you.

Which form came back?