What Paperwork Does a GC Require From a Sub?

By Wyatt Cooper · Published October 12, 2026 · 6 min read

Key takeaways

Expect to send a W-9, a certificate of insurance with its endorsements, your contractor license, and the signed subcontract before you mobilize.
A certificate of insurance is information only: the GC also wants the additional-insured and waiver-of-subrogation endorsements the subcontract names.
Without a correct taxpayer identification number on a W-9, a payer may have to withhold 24% of reportable payments: $2,400 on a $10,000 payment.
Lien waivers are the recurring paperwork: a conditional waiver with each pay app and an unconditional one once the money arrives; in states with statutory waiver forms, use the exact form.

Before a subcontractor starts work, a general contractor usually requires a signed subcontract, a Form W-9, a certificate of insurance showing the coverages and limits the subcontract sets, with the additional-insured and waiver-of-subrogation endorsements, a contractor license where the state requires one, and often a written safety program. Some jobs add bonds or prevailing-wage payroll. Each month the GC also asks for lien waivers with the pay app. Check your subcontract for the exact list.

Why the GC asks for all of it

The GC is passing down its own obligations. The owner's contract makes the GC carry insurance, pay its subs, keep the site safe and deliver a lien-free job; the GC's only way to meet those is to require the same things from each subcontractor. That is why the requests arrive in a bundle at award, and why a missing document can hold a payment months later.

The documents, one by one

What a GC commonly requires from a subcontractor, and when
Document	Who issues it	When	What the GC checks
Signed subcontract	GC drafts, sub signs	Before work	Scope, schedule, schedule of values, insurance and payment terms
Form W-9	The sub	Before the first payment	Legal name, tax classification and taxpayer identification number
Certificate of insurance	The sub's insurance agent or broker	Before work, and at each renewal	Coverages, limits, policy dates and the certificate holder
Endorsements	The insurer, through the agent	With the certificate	Additional insured, waiver of subrogation, primary and non-contributory, as the subcontract asks
Contractor license	The state or local licensing board	Before work	License number, classification for the trade, expiry
Safety program	The sub	Before work	A written program, and often training records
Bonds	The sub's surety	Before work, if required	Performance and payment bond amounts and surety
Lien waivers	The sub	With every pay app and after each payment	The right form, amount and through-date

The W-9 and backup withholding

Form W-9 gives the payer your correct taxpayer identification number so it can file information returns (IRS). The GC keeps it and does not send it to the IRS; it uses the TIN for returns such as Form 1099-NEC. If you do not provide a TIN, or provide an incorrect one, the payer may have to start backup withholding, and the IRS sets that rate at 24% of reportable payments (Instructions for the Requester of Form W-9).

Worked out: on a $10,000 reportable payment, 24% is $2,400 withheld, and you receive $7,600. Send the W-9 with your signed subcontract and it never comes up. If your company is a single-member LLC treated as a disregarded entity, the instructions put the owner's name on line 1 and the LLC's name on line 2.

The certificate of insurance is not the coverage

Most GCs want the certificate on the ACORD 25, the Certificate of Liability Insurance. ACORD itself is clear that a certificate "is NOT an insurance policy, and does not serve to provide, endorse, amend, extend, or alter in any way the terms of an insurance policy"; only an endorsement changes coverage, and naming a contract on the certificate "does not provide coverage" (ACORD certificates FAQ). That is why GCs ask for the endorsements themselves.

Ask your agent for the certificate and the endorsements together, with the GC (and the owner, if the subcontract says so) as additional insured.
Match the limits to the subcontract's insurance exhibit before you send it; a certificate below the required limit gets rejected.
Calendar every policy's expiry date. An expired policy usually puts your payments on hold until the renewal certificate is in.

License, safety program and the rest

Licensing is state law, and in some places local: whether your trade needs a license, and for what size of job, varies. Check the board in the state the project is in. For safety, many GCs ask for a written program. OSHA's Recommended Practices for Safety and Health Programs, with a construction version, are guidance rather than a rule, built on seven core elements from management leadership to communication among host employers and contractors (OSHA); they are a reasonable outline if you need to write one. On prevailing-wage or public jobs, expect certified payroll as well.

A filled-in checklist

Ridgeline Plumbing, Harbor Point Offices, before mobilization

Subcontract: Signed and returned
Form W-9: Sent with the subcontract
General liability certificate: Received; limits match the insurance exhibit
Additional insured endorsement: Requested from the agent, due Friday
Workers' comp certificate: Received; expires in 5 weeks, renewal calendared
Auto and umbrella certificates: Received
Contractor license: Plumbing classification, number and expiry sent
Safety program: Written program sent
Payment and performance bond: Not required on this subcontract

A fictional plumbing sub's compliance checklist at award

The one open item, the endorsement, is the one most likely to hold the first payment. Chase it before the first pay app, not after. For what each month's billing needs, see how to fill out a pay application as a subcontractor; for the GC's side of the same step, how to buy out a construction job.

How it works in Conflo

When a GC runs Compliance in Conflo, a sub sees only its own company's requirements: general liability, auto, workers' comp and umbrella certificates, W-9s, contractor licenses and lien waivers. Each request arrives with a due date and a note; you turn in the document with its expiry date and the carrier, policy or license number, and the GC approves it or rejects it with a note on what to fix. A missing, expired, rejected or unreviewed document that the GC marks as required for payment puts your company on payment hold, and your pay apps show what is holding payment.

The same pay app as the electrical subcontractor sees it in Conflo: waiting on the GC, the payment steps, what is holding payment, the application summary and the schedule of values with this period, stored and to-date amounts. — A sub's pay app in Conflo: the payment steps and what is holding payment, beside the summary and schedule of values.

Not tracked in Conflo today: endorsements as their own documents, safety programs and bonds.

The bottom line

The paperwork list is long but predictable: subcontract, W-9, certificate with endorsements, license, safety program, and waivers every month. Send it as a set at award and keep the expiry dates on a calendar.

Most payment holds from compliance are an expired certificate or a missing endorsement. Both are fixed with one call to your agent before the pay app goes in.

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Sources

About Form W-9, Request for Taxpayer Identification Number and Certification — Internal Revenue Service. Read October 16, 2026.
Instructions for the Requester of Form W-9 (Rev. March 2024) — Internal Revenue Service. Read October 16, 2026.
Certificates of Insurance: Frequently Asked Questions — ACORD. Read October 16, 2026.
Recommended Practices for Safety and Health Programs — Occupational Safety and Health Administration. Read October 16, 2026.

Questions

What documents does a subcontractor need before starting work?

Usually a signed subcontract, a Form W-9, a certificate of insurance with the required endorsements, a contractor license where required, and often a written safety program. Some jobs also require bonds. The subcontract lists what that GC needs.

Does the GC send my W-9 to the IRS?

No. The requester keeps the W-9 and uses your taxpayer identification number to file information returns such as Form 1099-NEC.

Is a certificate of insurance enough to be an additional insured?

No. ACORD says a certificate does not change a policy; only an endorsement does. GCs ask for the additional-insured endorsement itself.

Why is my payment on hold for compliance?

Usually because a required document expired, was rejected or was never sent: most often an insurance certificate past its expiry date. Send the renewal and ask the GC to release the hold.

What is the backup withholding rate?

The IRS's instructions for Form W-9 set it at 24% of reportable payments, when a payee fails to give a correct taxpayer identification number or certify as required.