Subcontractor Invoicing: How to Bill and Get Billed Properly

Subcontractor relationships live or die on clarity: who invoices whom, for what, under which flow-down terms, and how fast cash moves after the end client pays—if that is your arrangement.

Construction and trades associations such as AGC publish extensive guidance on pay-when-paid and documentation; professional services subs should borrow the same rigor even without mechanics liens.

If you are the subcontractor (billing up)

Mirror the prime contract

Your SOW should reference rates, milestones, expenses, and approval paths. If the prime needs backup for their client, attach it proactively—see expense invoicing.

Invoice like AP will scrutinize

Use PO or work order numbers, phase codes, and dates. Tie to milestones or progress billing when applicable.

Understand payment timing

Pay-when-paid clauses shift risk. Price and cash reserves accordingly. Ask for partial retainage release schedules in writing.

If you are the prime (billing clients + paying subs)

Separate client invoices from sub costs

Client invoices should show your value distinctly from pass-throughs unless the contract mandates a bundled presentation—either way, avoid margin ambiguity.

Internal controls

Use approval workflows before paying large sub invoices. Keep an audit trail linking sub bills to client revenue.

1099s, VAT, and withholding

Tax form obligations vary by country and entity type. Coordinate with your accountant; surface tax IDs on invoices as required in tax compliance.

Disputes between tiers

When an end client disputes work, the prime and sub should document facts quickly—see disputed invoices. Avoid unilateral chargebacks to subs without following the subcontract’s dispute clause.

Payment hygiene

Pay subs on predictable cycles; they will prioritize your next project. When you must delay, communicate a date, not silence. For your own cash flow, automate reminders on client invoices.

Cash timing between tiers

Model prime receipt to sub pay lag explicitly in your forecasts—working capital can vanish when clients pay slowly but subs expect net fifteen. Consider pay-if-paid only with counsel; some jurisdictions limit enforceability. Publish a lien waiver or equivalent paperwork schedule if your industry expects it. When subs invoice expenses, require their receipt pack the same day you need to pass costs upstream. Align insurance and certificate-of-insurance expirations with project timelines so procurement does not stall your invoices.

Closing checklist

Monthly, age payables to subs versus receivables from clients. File lien releases when trades complete. Match 1099 or local equivalent thresholds before year-end. Centralize COI PDFs with dates visible. Review disputed invoices playbooks when primes and subs disagree. Update rate cards when material costs spike.

Metrics and cadence

Track sub payables aging versus client receivables aging—dangerous wedges need treasury attention. Measure lien or waiver defects per month; paperwork stalls cash. Review pass-through expense dispute rates separately from labor. Compare margin by tier (prime versus sub work) to see where risk concentrates. Align metrics with expense invoicing hygiene upstream.

Final takeaway

Prime and sub success is mostly documentation and timing. Pay subs as fast as you reasonably can when clients pay you—reputation is working capital. Never let informal side deals with subs contradict the prime contract. When conflicts arise, write first, argue second, and keep every version in your trail.

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Subcontracting structures (2026)

The right structure depends on liability, client preferences, and your operational role. White-label resale is most common for agencies; direct subcontract is most common for "introducing" relationships.

Step-by-step: Subcontracting a portion of your work

Step 1: Document the subcontract relationship in writing

Master Service Agreement between you and the subcontractor. Specifies: scope of subcontracted work, payment terms (you pay sub), deliverable timing, IP assignment, confidentiality. Don't subcontract without written agreement.

Step 2: Get sub's W-9 (US) or W-8BEN (international) before paying

For US subs: W-9 with SSN or EIN, kept in your files. For international: W-8BEN (individual) or W-8BEN-E (entity) — required to determine withholding. Without these forms, IRS may require backup withholding.

Step 3: Maintain insurance and liability provisions

Standard sub agreement includes: sub maintains general liability insurance, sub liable for their work product, you indemnified for sub's actions. Without this, sub problems become your problems.

Step 4: Pay sub on time, ideally before client pays you

If you pay 30 days after client (typical), build into sub agreement: "You'll be paid 30 days after [client] pays us." Some prefer to pay sub immediately and float — depends on cash flow and how much you trust the client.

Step 5: Issue 1099-NEC at year-end (US) for $600+

US payments to non-employee subs above $600 require 1099-NEC by January 31 of following year. Sub then files this on their personal/business taxes. You file 1099-NEC + 1096 transmittal with IRS.

Common subcontracting scenarios

Solo freelancer hiring one sub: Hire designer A for the design portion of a $20K project; pay them $8K. Issue 1099-NEC at year-end. Document the work split clearly. Solo overhead acceptable; one sub manageable.

Agency with multiple subs: 5+ subs working across different client engagements. Need formal contractor management: tracking hours, invoicing, payments, 1099 issuance. Software (Gusto, Bill.com) handles at scale.

White-label resale: Client thinks you're solo; you actually subcontract design portion to a partner. Risky if discovered; legal in most jurisdictions but trust-damaging if exposed. Be clear with subs about confidentiality.

International subcontractor: Indian designer for $5K subcontract. Pay via Wise or PayPal. Document W-8BEN. May trigger FBAR if you have foreign bank account control. Talk to CPA familiar with international.

Frequently Asked Questions

Do I need a written sub agreement?

Yes — for protection and to clarify terms. Without it, disputes become messy. Standard MSA + project addendum is sufficient. Templates available from Bonsai, Rocket Lawyer, etc.

Should I markup the sub's rate?

Yes if you're providing real value (project management, client relationship, quality assurance). 25-50% markup is industry standard for white-label resale. If you're just passing through, 10-20% acceptable.

What if the sub messes up?

Your sub agreement should address quality. If sub-delivered work is poor, you're on the hook for client. Document quality issues with sub; pursue financial remedy per agreement (offset against future payments, recovery of overage).

Do I need to issue 1099 if I paid via PayPal?

PayPal handles 1099-K reporting for transactions above $5,000 (2024 threshold). Direct ACH or wire payments still require you to issue 1099-NEC. Cryptocurrency payments: still you, not the platform.

What about international subs and 1099?

Foreign individuals/entities don't get 1099-NEC; they get W-8BEN paperwork. Your withholding requirement depends on country and treaty. Most US-foreign service work is exempt from US withholding under treaty; verify per country.