The Subcontractor Onboarding Checklist: Compliance Edition
Every experienced construction finance team has the same observation: the subcontractors who cause the biggest downstream problems almost always had something incomplete at onboarding. A COI that listed the wrong certificate holder. A W-9 that was never collected because the PM assured AP it would arrive 'with the first invoice.' A license that expired two months before the contract was signed. The failure was seeded before the first day of work — it just didn't become visible until the payment gate closed on it.
Subcontractor onboarding is a one-time investment that pays dividends for the life of the relationship. A disciplined checklist run before the first PO issues catches 90% of the administrative issues that otherwise surface during the project, and it creates the baseline record that makes every subsequent audit, dispute, and renewal easier.
Before collecting a single document, decide whether this sub is someone your GC actually wants to do business with. Prequalification is the rough filter — a short set of questions that reject subs who would fail deeper scrutiny, before the full onboarding effort is spent on them.
Prequalification questions every new sub should answer
- Legal name, DBA, entity type, and state of formation
- Year founded and years in operation under current ownership
- Primary contact, AP contact, and safety officer (with email and phone for each)
- Approximate annual revenue and peak bonding capacity
- Number of W-2 employees and typical 1099 workforce size
- Three reference contacts from recent projects of similar scope and value
- Disclosure of any OSHA citations, legal actions, or bankruptcies in the past 5 years
- States licensed to operate in
Prequalification is not a legal adversarial process — it is an efficiency step. The sub that declines to answer these questions, or provides evasive answers, is telling you something valuable. The sub that answers completely is signaling that the relationship is worth further investment.
Once a sub passes prequalification, tax and entity documentation comes first — before anything else. No other onboarding step should complete until these do, because each downstream document (contract, insurance, license) depends on having the sub's legal identity correctly anchored.
Required tax and entity documents
- Form W-9 for US vendors — completed, signed, dated, with TIN that matches IRS records
- Form W-8BEN-E for foreign entities — completed, with treaty claim identified if any
- Secretary of State filing or good-standing certificate for the state of formation
- DBA filing if operating under a trade name different from the legal entity name
- EIN verification letter from the IRS (Form CP-575 or equivalent) for TIN confirmation
- IRS TIN Matching Program verification result
The discipline here is to collect and verify before the first payment, not to paper-over the gaps later. A sub without a verified TIN gets paid with 24% backup withholding per IRS rules — which immediately creates a vendor relationship problem and may expose the GC to liability if the withholding is not remitted correctly.
Insurance is the second critical dependency. Contract signing should not precede insurance verification because the contract will typically specify coverage minimums that the sub needs to confirm are in place.
Insurance documentation to verify
- Current ACORD 25 Certificate of Insurance showing all required coverages
- Additional Insured endorsement (actual policy endorsement, not just COI notation) — CG 20 10 and CG 20 37
- Waiver of Subrogation endorsement on general liability, auto, and workers' compensation
- Primary and non-contributory language on the general liability
- A.M. Best rating of each carrier (A- or better is common minimum)
- Workers' compensation statutory coverage in every state where work will be performed
- Coverage limits meeting or exceeding the contract requirements
- Expiration tracking set up for automated reminder before renewal date
License requirements vary substantially by state and trade. Construction license verification is not as standardized as insurance verification, but it is equally consequential — a sub performing unlicensed work in a state that requires a license can void the contract and in some states trigger GC liability for remediation.
Licensing documents to collect and verify
- Contractor license(s) for every state where the sub will perform work on this project
- Trade-specific licenses (electrical, plumbing, HVAC, etc.) where required
- Business license in the municipality of the jobsite if locally required
- Public Works Contractor Registration (California, New Jersey, and other states with equivalent requirements)
- Verification of license status with the issuing agency — not just the paper certificate
- Expiration dates logged with renewal reminders
License verification via the issuing agency's public database is a separate check from collecting the license certificate. Suspended licenses can look like active ones on a PDF. Every contractor license board and every state contractor license database is free to query. The five minutes of verification per sub is cheap insurance against non-licensed-work claims.
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Banking information is the highest-stakes data captured during onboarding — because it is the target of most external invoice fraud. Every sub should be onboarded with the assumption that a bad actor will eventually attempt to change the banking information, and the onboarding record should be the baseline against which those changes are verified.
Banking data capture protocol
- Bank name, routing number, account number, account type
- Authorized signer name (should match a contact on the sub's other documentation)
- ACH authorization form signed by an officer of the sub
- Voided check or bank letter confirming the account belongs to the sub's legal entity
- Verification call to the bank confirming the account exists and is owned by the sub
- Archive of the original setup — timestamped, with who set it up and who approved it
By the time the subcontract is ready to sign, every preceding stage should be complete. The contract formalizes the relationship and references the documentation already on file — insurance minimums, lien waiver forms, scope of work, payment terms, retainage percentage, and indemnity structure.
Contract signing checklist
- Legal names on the contract match W-9/W-8 and entity formation documents exactly
- Insurance minimums in the contract align with the COI on file
- Lien waiver forms referenced are state-compliant for the project jurisdiction
- Scope of work is specific enough to enable accurate pay-app review
- Payment terms (net X days) are consistent with the GC's standard AP policy
- Retainage percentage matches the prime contract flow-down
- Indemnity, defense, and hold-harmless language is at the sub's coverage level
The final onboarding step is operational: connecting all the documentation collected to the AP payment gate. The rule is simple — no invoice can be paid to a sub with incomplete documentation. When the next COI renewal comes due, payment blocks until renewal. When a license expires, payment blocks. When a lien waiver is missing for a prior period, payment blocks.
The gate is an operational control that prevents the drift that otherwise happens: an onboarded sub whose documentation lapses without being caught, whose invoice gets paid under time pressure, and whose compliance status only surfaces when a third-party audit asks for the record.
Manual subcontractor onboarding has two chokepoints. The first is document collection — the sub needs to provide a dozen items, the AP team needs to chase them, and the project is usually already trying to start. The second is verification — each item collected needs to be checked, and manual verification scales poorly across dozens of new subs per year.
Automated onboarding platforms front-load the collection: the sub fills out a self-service portal that requests every item in a structured way, with file upload for documents, TIN matching integrated, COI OCR and endorsement verification built in, and license lookup against state databases. The AP team's role shifts from chaser-and-checker to exception-handler — reviewing only the subs whose submissions fail automated verification.
Subcontractor onboarding is the most leveraged compliance workflow in construction finance. The work done in the days before a new sub starts determines how smoothly the payment relationship runs for the next 18 months. Every hour invested in disciplined onboarding saves multiple hours of friction and reduces real dollar exposure across insurance gaps, tax liabilities, and license disputes. The checklist above is the minimum viable version; the automation version is the one that scales.
Written by
Marcus Reyes
Construction Industry Lead
Spent twelve years running AP at a $120M general contractor before joining Covinly. Lives in the world of AIA G702/G703, retainage schedules, and lien waiver deadlines. Writes about the construction-specific workflows that generic AP tools get wrong.
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