How do I collect an unpaid invoice as a subcontractor?
How to collect an unpaid invoice when you're a subcontractor
Short answer
As a subcontractor, you can file a mechanics lien against the property where the work was performed — even if your contract was with the general contractor, not the owner. You typically have 60–90 days from completion to file. In many states you must first serve a 'preliminary notice' within 20 days of starting work. Act before the deadline; missed lien rights are permanent.
The mechanics lien is the subcontractor's most powerful collection tool, and it's underused because most subs don't know the deadline. A lien attaches to the real property itself — the building or land — not just to the GC's assets. This means even if the GC disappears or goes bankrupt, you have a claim against the property owner, who typically has something worth protecting. Lien filings are public record and cloud the property title, making it nearly impossible to sell or refinance until the lien is resolved.
Preliminary notice (also called a 'notice to owner' or '20-day notice') is a prerequisite for lien rights in most states. It must be served on the property owner, the GC, and the lender (if any) within a defined window — often within 20 days of first furnishing labor or materials. If you miss it, you may lose your lien rights entirely. This is paperwork that takes 20 minutes but must happen on day one of every project, not after you have a payment problem.
Pay-when-paid clauses in subcontract agreements say the GC only owes you after they've been paid by the owner. These clauses are enforceable in most states, but courts in some jurisdictions interpret them narrowly — the GC must make a genuine effort to collect from the owner before invoking the clause, and an indefinite non-payment by the owner doesn't indefinitely delay your payment. If the clause is being used as a shield rather than a legitimate trigger, document your demand to the GC and the GC's inaction.
Joint check agreements are another useful tool in construction payment chains. You request that the owner (or a higher-tier contractor) issue a check made payable to both the GC and to you jointly. This ensures the funds don't disappear inside the GC's cash flow. Experienced subs negotiate this into their contracts on large projects.
If lien rights and negotiation fail, your remaining options are demand letter → small claims (for smaller amounts) → civil suit. Construction disputes often end in mediation because both sides face ongoing project exposure. Syntharra's AI calling can handle the GC follow-up calls in the same automated cadence as direct-client invoices — the compliance rules are the same because it's still a first-party commercial receivable.