ISO Additional Insured Forms Explained: CG 20 10, CG 20 26, CG 20 37, and More

Your customer just emailed a contract that says: "You must add us as an additional insured using CG 20 10 and CG 20 37." You stare at the page. What do those numbers mean? Why two of them? And do you actually have them?

This guide gets you a clear answer in five minutes.

Get a same-day quote with the right forms built in → · Or call 425-209-1206

The Six Forms at a Glance

Six ISO forms cover almost every customer request you'll ever see. Here's what each one does in plain English:

Form	What it does	Best for
CG 20 10	Adds one specific customer for work in progress	Single-job contracts
CG 20 11	Adds a landlord or building manager	Working in a leased space
CG 20 26	Adds one specific customer for ongoing + completed work	Sophisticated commercial contracts
CG 20 33	Adds any customer required by a written contract — work in progress only	Default blanket form
CG 20 37	Adds one specific customer for completed work	Paired with CG 20 10
CG 20 38	Adds any customer required by a written contract — ongoing AND completed work	What you want

"Ongoing" vs "Completed" matters. Most claims happen during the job — a worker drops a ladder on someone, a forklift bumps a parked car. Some claims happen after the job — a railing fails six months later, a roof leaks in the first storm. Forms that only cover "ongoing operations" leave a gap on the second type. And most contracts require both.

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Each Form — Quick Read

CG 20 10 — Named customer, work in progress

The form GCs ask for most. It names a specific customer (by exact legal name) as an additional insured for work in progress only. Once the job's done and you've left, this form stops covering them.

When you need it. A GC, owner, or project manager wants their name on your policy for the length of your job. Common on residential, smaller commercial, and one-off contracts.

The catch. It does NOT cover claims from work you already finished. If a GC has a claim from your work six months after the job ends, this form alone won't help them. You'd also need CG 20 37.

Edition dates. There are several editions of CG 20 10 (07 04, 04 13, and others). Newer editions are usually narrower. If your contract names a specific edition, your policy has to match.

CG 20 11 — Named landlord or premises manager

Used when you're a tenant or working inside someone else's building. It names a specific landlord, building manager, or property owner for liability tied to your work on their property.

When you need it. A lease says "add the landlord as an additional insured." Or a property manager requires it before you can start work in their building.

CG 20 26 — Named customer, broad coverage

Names a specific customer for both work in progress AND completed work. Broader than CG 20 10 alone. Most carriers prefer the two-form approach (CG 20 10 + CG 20 37) because it gives them more control, so you see this one less often.

When you need it. A sophisticated commercial contract that wants single-form, broad coverage instead of two scheduled forms.

CG 20 33 — Blanket, work in progress only

The blanket version of CG 20 10. Adds any customer required by a written contract — automatically, no scheduling needed. But only for work in progress.

When you need it. Most contractor GL policies include this by default. It saves you from getting an individual form for every new GC.

The catch. Like CG 20 10, this only covers work in progress. To get blanket coverage for completed work, you need CG 20 38.

CG 20 37 — Named customer, completed work

The completed-work companion to CG 20 10. Names a specific customer for completed work only.

When you need it. Almost always paired with CG 20 10 in construction contracts. Together they cover both phases.

Why it matters in WA. Washington's deadline for construction defect claims can run years after you finish a job. CG 20 37 is what protects a GC if a claim hits two or three years out.

CG 20 38 — Blanket, both phases

The form most contractors actually want. Adds any customer required by a written contract, and covers both work in progress AND completed work. One form, full coverage, automatic.

Why it's the winner. No scheduling. No per-project paperwork. Covers both phases. Most GCs and owners accept it.

Watch out. Some carriers issue CG 20 33 (blanket ongoing) but not CG 20 38 (blanket both). If your policy only has the ongoing-only blanket, you've got a gap on completed work. Worth checking.

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How to Read a Contract's Insurance Requirement

Most contracts list the forms they want. Two examples you'll see often:

> "Subcontractor shall add Owner and General Contractor as Additional Insureds using ISO Form CG 20 10 for ongoing operations and ISO Form CG 20 37 for completed operations."

Clear request. You need both forms, naming both the Owner and the GC.

> "Additional insured status shall be provided on a primary and non-contributory basis."

This is a layer on top of the AI requirement. Your form also has to be primary (your policy pays first) and non-contributory (your insurer eats the full loss before the customer's insurer pitches in). See our primary and non-contributory guide for what that means.

If a contract is vague — just says "add us as additional insured" — ask for clarification or default to CG 20 38 (blanket, both phases). It's the safest bet and almost never rejected.

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What Most WA Contractors Should Have

If you handle 5+ contracts a year, here's the setup that covers almost every customer request:

• CG 20 38 (blanket, both phases) — covers nearly every contract requirement
• Blanket waiver of subrogation — required by most big clients
• Blanket primary and non-contributory — required alongside AI on most large contracts
• CG 20 11 added when a specific landlord or property manager asks for it

This combo handles 90% of contract requirements without per-project paperwork, processing delays, or extra fees.

If you only do a few jobs a year — or only one customer — scheduled forms (CG 20 10 + CG 20 37 naming that one customer) can work. But the second you start handling multiple GCs, blanket coverage saves real time and money.

Frequently Asked Questions

What's the difference between CG 20 10 and CG 20 37? CG 20 10 covers work in progress. CG 20 37 covers completed work. Most contracts ask for both.

Is CG 20 38 the same as "blanket additional insured"? Yes — CG 20 38 is the most common ISO form for blanket coverage that includes both phases. Some carriers use their own form numbers with similar language; the coverage is the same.

My contract requires "CG 20 10 11 85" — what's the 11 85? Those are edition dates. CG 20 10 11 85 is the November 1985 edition. Older editions are usually broader. Many carriers don't issue this one anymore. If a contract requires an edition you can't get, you may need to negotiate or use a newer-edition equivalent.

What if my carrier uses a proprietary form instead of CG 20 38? Most carriers have their own version with similar coverage. Your COI lists the form number used. If a GC specifically demands an ISO-form CG 20 38 and your policy uses a proprietary form, your agent can either negotiate with the GC or switch you to a carrier that issues the ISO form.

Can I get same-day blanket additional insured coverage? Yes. Most contractor GL policies bind same-day. SmartInsured sets up blanket AI as standard. You can have a Certificate of Insurance with the right language in your hands within an hour of binding.

Does my General Liability policy automatically include these forms? Some do, some don't. Standard policies often include CG 20 33 (blanket, ongoing) but not the completed-work version. Ask your agent or read your policy to confirm CG 20 38 is on it.

Is there an AI form for commercial auto policies? Yes — different ISO forms apply to commercial auto (like CA 20 48). They work the same way but apply to your commercial auto policy, not your GL. If a contract requires AI on both, you need both forms.

Two Ways to Get the Right Forms on Your Policy

If your contract asks for specific forms and you're not sure your current policy delivers:

1. Get a same-day quote — send us your customer's request and we'll quote a SmartInsured policy with CG 20 38, waiver, and P&NC built in. Free, no obligation. 2. Call 425-209-1206 to read us the contract clause directly — real WA agents, no menus

Same-day binding and certificates of insurance available for Washington contractors. Don't let a paperwork gap cost you a job.