Washington Subcontractor Insurance Requirements: A General Contractor's Complete Guide

TL;DR: Washington is one of a handful of exclusive state-fund workers' comp states, meaning every sub you hire must carry industrial insurance through L&I — not a private insurer — or be legally self-insured. A standard COI won't show this coverage; you must verify it directly at lni.wa.gov. On top of that, all contractors must be registered with L&I (RCW 18.27) and carry GL and a surety bond before setting foot on a job.

If you've worked in multiple states, Washington will feel different the moment you try to verify a subcontractor's workers' comp. There's no Travelers, Zurich, or Hartford policy number to look up. Washington runs its own industrial insurance system through the Department of Labor & Industries (L&I), and every employer in the state — including your subs — must pay into it. Subs who skip this aren't just uninsured; they're breaking state law, and the liability can land on you.

This guide covers everything Washington GCs need to know: contractor registration, GL requirements, how the state WC system actually works, lien laws, and a compliance checklist you can hand off to your admin team.

Washington Contractor Registration: Not a License, But Just as Important

Washington doesn't use the term "license" the way most states do. Contractors are registered through the Washington Department of Labor & Industries under RCW 18.27. The distinction is more than semantic — registration is tied directly to your business's insurance, bonding, and tax compliance, and it can be verified by anyone in about 30 seconds.

Who Must Register

Nearly every contractor doing work in Washington for compensation must register, including:

• General contractors (residential and commercial)
• Specialty contractors (electrical, plumbing, HVAC, framing, roofing, and all trades)
• Out-of-state contractors working on Washington projects

Homeowners doing work on their own property are exempt. Subs working entirely on one GC's payroll as employees (with L&I coverage deducted from wages) may also be exempt, but most independent subs operating as their own business entity must be registered.

What Registration Requires

To register with L&I (and maintain registration), a contractor must have:

• A Unified Business Identifier (UBI) number from the Washington Secretary of State
• A surety bond: $12,000 for general contractors, $6,000 for specialty contractors (verify current amounts at lni.wa.gov)
• General liability insurance meeting L&I's minimum limits (confirm current limits at lni.wa.gov — state floors are low; industry practice runs higher)
• An active L&I industrial insurance account, unless legally exempt

Verify any sub's registration in seconds at L&I's Contractor Verify tool: secure.lni.wa.gov/verify/. You'll see their registration status, bond info, and whether their insurance is on file. Make this lookup standard practice before any sub sets foot on a job.

Hiring an unregistered contractor is a misdemeanor under RCW 18.27.020 and can also expose you to liability for their employees' injuries and third-party claims that their unregistered GL policy might not properly cover.

General Liability Insurance Requirements

Washington sets minimum GL limits as part of contractor registration, but those state minimums are a floor — not what you should actually require from subs. In practice, Washington GCs require:

• $1,000,000 per occurrence for most residential and light commercial subcontractors
• $2,000,000 aggregate as standard across most trades
• $2,000,000 per occurrence for higher-risk trades (roofing, demolition, excavation) or commercial projects

Additional Insured Endorsement

Always require subs to add you as an additional insured on their GL policy using ISO endorsements CG 20 10 (ongoing operations) and CG 20 37 (completed operations). A certificate of insurance that just says "additional insured" in a remarks box is not the same thing — get the actual endorsement.

Washington courts have consistently upheld additional insured clauses, but if the endorsement isn't attached and the policy excludes coverage, you're fighting on your own dime when a claim hits.

Completed Operations Coverage

On longer or higher-value projects, verify that completed operations coverage extends for at least one year after project completion — longer on commercial work. Defect claims in Washington often surface 12-24 months post-completion, and you need the sub's policy to still cover them.

Workers' Compensation in Washington: The State Fund System

This is where Washington diverges sharply from most states, and where many out-of-state GCs get caught off guard.

Washington is an exclusive (monopolistic) workers' compensation state. Under RCW Title 51, virtually all employers with employees must purchase industrial insurance through the Washington State Department of Labor & Industries — not from private insurers like Liberty Mutual or Travelers. Private WC policies for most employers simply don't exist here.

The only exception is employer self-insurance, available to large employers who meet L&I's financial and safety requirements. True self-insured status is granted by L&I and is uncommon among small and mid-size contractors.

What This Means for COI Verification

When you request a certificate of insurance from a sub, don't expect to see a workers' comp section showing a private carrier and policy number. You won't find one for most Washington subs. Instead, you need to verify their L&I account status directly.

How to check a sub's L&I industrial insurance status:

1. Go to secure.lni.wa.gov/verify/
2. Search by business name or UBI number
3. Confirm their account is active and in good standing

Alternatively, ask the sub to provide their L&I account ID (their industrial insurance account number), and verify it yourself. A sub with no L&I account is not covered — and work performed by uncovered employees can trigger L&I assessments against your business.

Sole Proprietors and Partners

In Washington, sole proprietors and partners are not automatically covered by their own L&I accounts. They can voluntarily opt in to coverage, but many don't. If a sole-proprietor sub gets injured on your site and has no L&I coverage, you're in a difficult position — potentially liable for their losses under common law since there's no WC system backstop.

Ask every sole proprietor sub directly whether they've opted into L&I coverage. If they haven't, consider whether your contract should address this risk, or whether you should require them to opt in before starting work.

Out-of-State Subcontractors

Out-of-state subs performing work in Washington must either:

• Open an L&I account and carry Washington industrial insurance for their Washington-based employees, or
• Have coverage through an approved reciprocal arrangement (verify with L&I before assuming this applies)

A private WC policy from their home state doesn't satisfy Washington's requirements for work performed in Washington.

L&I Premium Payments and Compliance

L&I industrial insurance is funded by employer and employee contributions (quarterly payroll reports). Subs in good standing will have no delinquent L&I payments on their account. If L&I puts a lien on a contractor for delinquent premiums or assessments, it can become your problem on joint projects — particularly under Washington's retainage and lien laws.

Run the contractor verify lookup regularly, not just at onboarding. A sub can fall behind on L&I payments mid-project.

Washington Lien Laws (RCW 60.04)

Washington's mechanics' lien statute (RCW 60.04) is contractor-friendly — but it has pre-notice requirements that GCs need to manage closely.

Pre-Lien Notice Requirements

Subcontractors, suppliers, and laborers who are not in direct contract with the property owner must serve a pre-lien notice (sometimes called a "notice to owner") within 60 days of first furnishing labor or materials. Without this notice, they cannot perfect a lien later.

This matters to you as the GC because:

1. If a sub properly serves a pre-lien notice, you'll hear about it — and it signals they're protecting their payment rights. Acknowledge it.
2. If a sub doesn't serve the notice, they lose lien rights — reducing your exposure if there's a payment dispute.
3. If you're the direct contractor with the owner, you don't need to serve a pre-lien notice yourself, but you still must follow filing deadlines.

Lien Filing and Enforcement Deadlines

• Lien filing deadline: Within 90 days of the last date labor or materials were furnished
• Lawsuit to enforce the lien: Must be filed within 8 months of the lien filing date
• Release of lien bond: An owner can substitute a bond to release the lien from the property while the dispute is resolved

Lien Waivers

Washington doesn't mandate a specific lien waiver form by statute, but conditional and unconditional lien waivers are standard practice on Washington construction projects. Collect a conditional lien waiver (waiver conditioned on payment clearing) at each pay application, and swap for an unconditional waiver once payment clears.

For final payment, get an unconditional final lien waiver from every sub and major supplier covering all labor and materials furnished. Keep these on file for the duration of your statute of limitations exposure.

Retainage in Washington

On public works projects, Washington requires GCs to retain 5% of progress payments from subs (RCW 60.28). Private projects can set their own retainage terms by contract, but 10% is common in early project phases, often reducing to 5% once the project is 50% complete. Retainage can be substituted with an escrow arrangement if both parties agree.

W-9 and 1099 Requirements

Washington has no state income tax, which simplifies the W-9 picture somewhat — there's no Washington state withholding to worry about on 1099 income. However, federal 1099 requirements still apply on all sub payments:

• Collect a completed IRS Form W-9 from every sub before first payment
• File a 1099-NEC for any sub (individual, sole proprietor, or LLC taxed as a sole proprietor/partnership) paid $600 or more in the calendar year
• The IRS penalty for failure to file a required 1099 is $310 per form (2025–2026 rate)

Even though Washington has no state income tax return to worry about, the federal 1099 obligation remains. Don't let the lack of state complexity make you sloppy on the federal side.

Washington does have a Business & Occupation (B&O) tax on gross receipts. This is a tax on your revenue, not the sub's, but subs operating in Washington will be filing their own B&O returns. This doesn't create a withholding obligation for you — just be aware that subs sometimes mention it when you ask about tax forms.

Washington Compliance Checklist

Use this before work begins and revisit it quarterly on active projects.

Before a Sub Starts Work:

• Verify contractor registration at secure.lni.wa.gov/verify/
• Confirm GL policy is active: $1M/$2M minimum (or higher per your contract)
• Get Additional Insured endorsements (CG 20 10 + CG 20 37) naming your company
• Verify L&I industrial insurance account is active and in good standing
• Confirm sole proprietors have opted into L&I coverage (if applicable)
• Confirm out-of-state subs have Washington L&I coverage for Washington employees
• Collect completed IRS Form W-9
• Confirm sub's surety bond is in force (visible through contractor verify)

At Each Pay Application:

• Collect conditional lien waiver from sub (and major subs-of-subs if applicable)
• Verify contractor registration status is still active
• Check L&I account status for any new holds or delinquencies

At Final Payment:

• Collect unconditional final lien waiver from sub and major suppliers
• Confirm no outstanding L&I liens against the sub's account

At Year-End:

• Issue 1099-NEC to all qualifying subs by January 31
• File 1099 information returns with the IRS by the applicable deadline

How PaperBoss Handles Washington's Quirks

Washington's COI verification doesn't fit neatly into the typical "check the policy number" workflow because WC comes from L&I, not a carrier. PaperBoss tracks your subs' L&I account verification dates alongside their GL and other coverage, so your compliance dashboard reflects the full picture — not just what's on the certificate. You can set renewal reminders for GL and bond, and separately flag L&I verification intervals. Start a free PaperBoss trial to see how it handles Washington's state-fund WC requirement alongside standard COI tracking.

Frequently Asked Questions

Do Washington subcontractors need a contractor's license?

Washington uses "registration" rather than "licensing" for most contractors. All contractors doing work for compensation in Washington must be registered with L&I under RCW 18.27. Electricians and other specific trades also need separate trade licenses through L&I. Verify any sub's status at secure.lni.wa.gov/verify/.

Why doesn't my Washington sub's COI show workers' comp coverage?

Because Washington is an exclusive state-fund workers' comp state. Most WC coverage comes from L&I — not private insurers — so it doesn't appear as a private policy on a standard ACORD COI. Verify WC coverage by checking the sub's L&I account status directly at the L&I contractor verify tool.

What happens if I hire a subcontractor who isn't registered with Washington L&I?

Hiring an unregistered contractor is a misdemeanor offense in Washington (RCW 18.27.020). You also lose protection from liability for their employees' injuries and may face exposure to third-party claims that their unregistered GL policy might not properly cover. Always verify before starting work.

What are Washington's lien waiver requirements?

Washington doesn't mandate specific lien waiver forms by statute, but conditional and unconditional waivers are standard practice. Subs and suppliers not in direct contract with the owner must serve a pre-lien notice within 60 days of first furnishing labor or materials. Liens must be filed within 90 days of last furnishing labor or materials under RCW 60.04.

Does Washington require me to withhold taxes from subcontractor payments?

No state income tax withholding is required in Washington since the state has no personal income tax. Federal backup withholding applies if a sub fails to provide a valid W-9. You are still required to file 1099-NEC forms with the IRS for qualifying sub payments of $600 or more.

How much GL insurance should I require from Washington subcontractors?

State minimums for contractor registration are low — confirm current minimums at lni.wa.gov. In practice, Washington GCs require $1M/$2M from most subs, with higher limits for riskier trades (roofing, demolition, excavation) and commercial projects. Always require the Additional Insured endorsements (CG 20 10 and CG 20 37), not just a certificate notation.

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Washington's contractor compliance is manageable once you understand the L&I system — but if you treat it like every other state and just collect a COI, you'll miss the WC verification step that matters most. The contractor verify tool at L&I makes this easy if you build it into your onboarding workflow. If you're managing more than a handful of subs, PaperBoss can automate the tracking and alert you before coverage lapses mid-project.