Subcontractor Management for Contractors: How to Hire, Invoice, and Pay Subs

You took on a 12-bathroom remodel and bid it solo, but you cannot frame, plumb, tile, and trim that many rooms with two guys. You need a sub. Maybe two. Subcontractor management is the part of running a contracting business no one trains you for — and the mistakes here are expensive. The plumber you trust is booked for six weeks. The electrician you used last time charged 30% more than he quoted. And your client wants a single invoice, on your letterhead, with one payment due to one company.

Bid wrong on a sub’s rate and your margin disappears. Skip a written agreement and you eat the cost of defective work. Miss a 1099 deadline and the IRS sends a love letter.

This guide walks through the full subcontractor lifecycle: finding reliable subs, putting the right paperwork in place, handling sub invoices, marking up labor without losing the job, back-charging when work is wrong, and staying 1099 compliant. The goal is simple — keep your subs happy, your margins intact, and your client relationship clean.

What Counts as a Subcontractor (and Why It Matters)

A subcontractor is a separately licensed, separately insured business that you hire to perform a specific scope of work on your project. They are not your employee. They send you an invoice; you do not run them through payroll.

The IRS test is functional, not what you call them. A worker is generally a subcontractor if:

• They control how the work gets done. You specify the result; they pick the methods, hours, and crew.
• They supply their own tools and vehicles. Their truck, their compressor, their nail guns.
• They carry their own insurance. General liability and workers’ comp on their own policy, not yours.
• They work for other contractors too. Your project is one of many, not their sole income.
• They invoice you for completed work. No hourly timesheet you submit.

Misclassification is the most expensive mistake in this whole guide. If the IRS or your state labor board reclassifies a “sub” as an employee, you owe back payroll taxes (employer and employee portions), unemployment insurance, workers’ comp premiums, and potentially penalties. For deeper detail, see our guide on contractor vs. employee classification.

How to Find Reliable Subcontractors

The cheapest sub on Craigslist will cost you more than the most expensive sub at the supply house. Reliability beats price every time, because you only pay your sub once but you only get paid by your client when the work passes inspection.

Where good subs come from:

• Your supply house. Plumbing, electrical, and HVAC supply counters know who pays their bills, who takes care of customers, and who got banned for bouncing checks. Ask the counter guy who he would call.
• Inspector recommendations. Building inspectors see every contractor’s work in your county. They know who fails inspections and who gets cleared on the first walkthrough. A casual “you got anybody good for radiant heat installs?” while signing a permit goes a long way.
• Other GCs you respect. A trade you do not compete with has no reason to gatekeep their best subs. The framer you swap referrals with probably has a roofer you should know.
• Trade association directories. PHCC for plumbing, NECA for electrical, ABC and AGC for general construction. Members invest in their license and reputation.
• Job site poaching (do this carefully). When you walk a job site and the trim work is exceptional, ask who did it. Not who hired them — who did the actual work.

Vet every sub before they swing a hammer:

1. Verify their state contractor license is active. Most states have free online lookup.
2. Get a current certificate of insurance (COI) — general liability minimum $1M, workers’ comp current. Have your business listed as an additional insured.
3. Run their business name through your state’s department of labor for unpaid wage claims.
4. Ask for three references on similar-scope jobs and call all three. Skip the one they recommend most enthusiastically — that’s the cherry-picked one.
5. Walk a current or recent job site. Pictures lie. Job sites do not.

The Subcontractor Agreement (Use One, Always)

Handshake deals work right up until the moment they don’t. Then you are out tens of thousands of dollars with no paper trail. Every sub on every job gets a written agreement, period.

A solid subcontractor agreement covers ten elements:

1. Scope of work. Specific. “Install three-bathroom plumbing rough-in per attached plan A2.1, including all DWV and supply lines, supply valves at all fixtures, and pressure-test certification.” Not “do the plumbing.”
2. Materials responsibility. Who supplies what. If the sub supplies, mark it up. If you supply, get receipts.
3. Total price and payment schedule. Fixed price preferred. Progress payments tied to milestones, not dates. Final payment after inspection passes and lien release is signed.
4. Schedule and start date. Including penalties for unexcused delays if your project has them.
5. Change order process. Written change orders signed by both parties. No verbal scope changes. (Our scope creep prevention guide covers this in detail.)
6. Warranty. Standard is one year on workmanship. Manufacturer warranty on materials passes through to the GC and ultimately the client.
7. Insurance and license requirements. Sub must maintain GL and workers’ comp through final completion. COI on file before work starts.
8. Lien rights and waivers. Sub agrees to provide a conditional lien waiver on each progress payment and a final unconditional lien waiver on final payment.
9. Indemnification. Sub indemnifies GC for damages caused by sub’s negligence.
10. Termination clause. Conditions under which either party can terminate, and payment owed at termination.

Have a construction attorney draft your master subcontractor agreement once. Reuse it on every job with project-specific scope and pricing as an exhibit. The $500–$1,500 you spend on the attorney pays for itself the first time a sub disputes a back-charge.

Subcontractor Invoice Management

Once the work starts, paperwork volume explodes. On a project with four subs, you can easily process 20+ sub invoices over the course of the job. Treat sub invoicing the way you treat your own client invoicing — systematically, with a clear paper trail.

Receiving and Reviewing Sub Invoices

Every sub invoice needs to clear five checks before you cut a payment:

• Matches the agreement. The invoice amount and milestone language match what you agreed to.
• Work is verified complete. You or your foreman walked it and checked it off. Not “they said they finished” — you saw it.
• Lien waiver is attached. Conditional waiver for progress payments, unconditional for final.
• COI is still current. Insurance lapses happen. Verify before paying, especially on jobs that run more than 60 days.
• Tax ID is on file. W-9 with EIN or SSN. You cannot pay a sub more than $599 in a year without one (more on 1099 thresholds below).

If any of those five fail, the invoice goes back. Politely, in writing. “Hi Mike, before we can process this draw, can you send the conditional lien waiver and an updated COI? I’ll cut the check the same day they hit my inbox.”

Tracking Sub Costs Against the Job

This is where most contractors lose visibility — and lose money. You bid the job at a fixed price to your client. Every sub invoice is a debit against that price. If you cannot see, in real time, what you have committed to subs versus what you have invoiced your client, you are flying blind on profitability until the job closes out.

Set up a simple sub cost tracker for every project:

When the “balance” column starts to stretch beyond the milestones you have actually completed on the client side, you have a cash flow problem. Pronto Invoice’s project view links each sub bill to the parent project so you see committed-vs-invoiced margin in real time, without having to maintain the spreadsheet by hand — that is the part of the workflow that catches projects going underwater while you can still steer them.

Markup Strategy on Subcontracted Work

You do not pay a sub $10,000 and bill your client $10,000. You would lose money on the job because your overhead — insurance, license fees, project management time, the truck you drove to the supply house — is real, even on labor you did not perform yourself.

Standard markup on subcontracted work runs 15% to 25%, depending on:

• How much management the sub requires. A sub who shows up, executes, cleans up, and bills cleanly takes 15%. A sub who needs daily babysitting and four punch-list trips takes 25% or you stop using them.
• Project scale. On larger projects, percentage markup gets compressed because the dollar value already covers your overhead. A 15% markup on a $200,000 sub commitment is $30,000 — that is real money for project oversight.
• Risk you are absorbing. If you guarantee the sub’s work to the client, you carry warranty risk for a year. Price for that.

Some contractors disclose the markup line item (“Subcontractor: $50,000; GC management fee: 20%”). Others fold it into a single project price. Both are legitimate. Disclosure works on cost-plus contracts and government work; folded pricing works on fixed-price residential. Match the convention your client expects.

What is not optional: marking up at all. “I just charge what the sub charges me, I make my money on my own labor” is how single-truck contractors stay single-truck contractors. Your time and risk are real costs even when the sub is doing the swinging.

Back-Charging for Defective or Incomplete Work

Eventually a sub will deliver work that fails inspection, damages other trades’ work, or simply gets done wrong. When that happens, you back-charge — you deduct the cost of fixing the problem from the next payment owed to that sub.

Back-charging is high-friction. Do it wrong and the sub walks off the job, files a lien, or sues. Do it right and most subs accept the charge and fix the problem on the next job.

Back-charge ground rules:

1. Document the defect immediately. Photos, video, inspector’s correction notice if applicable. Date-stamped.
2. Notify the sub in writing within 48 hours. Email is fine. The notice should describe the defect, reference the agreement section the work fails, and request a remedy by a specific date.
3. Give the sub the first chance to fix it. Most subs would rather come back and fix their own work than pay for someone else’s. Document their response.
4. If they refuse or no-show, get competitive quotes for the remedy. You cannot back-charge for a remedy that was inflated. Two written quotes from comparable trades.
5. Provide an itemized back-charge with documentation. “$3,400 deducted from final payment per attached invoices and notice dated [X].”
6. Apply the back-charge to a future payment, not retroactively. Never demand the sub send you money. Net it from what you owe them next.

If the back-charge exceeds what you owe the sub on this project, you are entering collections territory. Run the numbers — sometimes eating a partial loss and severing the relationship is cheaper than two years in small claims.

1099 Compliance for Subcontractors

If you pay a sub $600 or more in a calendar year for services, you must file Form 1099-NEC with the IRS and send the sub a copy by January 31 of the following year. This applies to sole proprietors and single-member LLCs. It does not apply to subs operating as C-corps or S-corps (with limited exceptions for legal and medical services).

The compliance flow:

1. Before paying any sub their first dollar, get a completed W-9. This gives you their legal name, business name, tax classification, and tax ID. No W-9, no payment.
2. Track all payments by sub for the calendar year. Year-to-date totals per sub, per business name and tax ID combination.
3. By January 31, file 1099-NEC for any sub paid $600+ during the year. File copies with the IRS, send Copy B to the sub, and keep Copy C for your records.
4. Penalties scale. $60 per form if filed within 30 days late, $120 per form by August 1, $310 per form after August 1, and $630 per form for intentional disregard.

Materials reimbursements where the sub passed through cost without markup are gray. Most contractors include them in 1099 totals to be safe. Consult your CPA for your specific situation. For deeper coverage, see our 1099 requirements for small business guide.

Frequently Asked Questions

What is the difference between a subcontractor and an independent contractor?

The terms are often used interchangeably in construction. Technically, a subcontractor performs work under a prime contract — you have a contract with a client, and your sub has a contract with you. An independent contractor is a broader tax classification describing anyone who is self-employed and not an employee. In practice, your subs are both: they are independent contractors (tax status) who are also subcontractors (contract structure).

Do I need a written subcontractor agreement for small jobs?

Yes. Even a one-day job can produce a dispute — defective work, unpaid balance, scope disagreement. A single-page agreement covering scope, price, payment terms, and insurance requirements takes 10 minutes to send and sign. The handshake deal that goes wrong takes months and thousands of dollars to resolve.

When do I withhold payment from a subcontractor?

You can withhold payment when work is incomplete, fails inspection, lien waivers are missing, or insurance is lapsed — but only up to the amount reasonably at risk. Withholding entire progress payments as leverage for unrelated issues is a fast path to a mechanics lien. Document every withholding in writing, citing the specific contract clause.

How do I handle a subcontractor who abandons the job mid-project?

Document the abandonment in writing the day it happens (certified mail or email with read receipt). Secure the site and photograph incomplete work. Get two competitive quotes for completion. Calculate the cost difference between your original sub contract and the completion cost — that is your damages. Apply any unpaid contract balance first; pursue the difference through small claims or your attorney depending on the amount.

Putting It All Together

Subcontractor management is risk management. Every step in this guide — the vetting, the agreement, the invoice review, the lien waivers, the back-charge process, the 1099 paperwork — exists because a contractor before you took a shortcut and got burned.

Build the system once. Use it on every sub, every job:

• Pre-job: License verification, COI, signed agreement, W-9 on file.
• During job: Documented scope completion before each progress payment, conditional lien waiver attached to each draw, photos of any concerns the day they happen.
• Post-job: Final inspection signed off, unconditional lien waiver, final payment, year-end 1099 reconciliation.

The administrative overhead feels heavy on your first project. By job five, it is reflexive. The contractors who scale past the one-truck mark are the ones who treat subcontractor management as a system, not a relationship-by-relationship improvisation.

If you are looking for a way to track sub invoices against client invoices in real time so you always know your project margin, Pronto Invoice’s project view was built for exactly that workflow — bid, sub commitments, client billing, and remaining margin in one screen so you catch projects going underwater while you can still steer them.