When It Makes Sense to Sue for Unpaid Invoices

How to read the warning signs, understand your claims, and know when a lawyer needs to be in the room

Illustration: How to read the warning signs, understand your claims, and know when a lawyer needs to be in the room

Every business owner has been there. You did the work. You delivered the product. You sent the invoice. And then — nothing. Or partial payments that stopped without explanation. Or a phone call promising the check is coming, followed by more silence. Or a customer who disputes the amount owed but can't quite explain why.

At some point, the question becomes unavoidable: is it time to sue?

The answer depends on factors most business owners don't think about until they're already in trouble: what kind of claim you actually have, what documentation you've been keeping, whether a limitation period is quietly ticking against you, and whether the structure of your relationship with the non-payer gives you more options — or fewer — than you realize.

Missouri courts have worked through every major variation of the unpaid-invoice problem, from a motorcycle helmet company chasing a single distributor to a subcontractor staring at $553,000 in work the general contractor refused to pay, to a food distributor that waited too long and lost a winnable case on a technicality. The cases below cover the full landscape — what your claim looks like, what kills it, what protects it, and what signals that it's time to stop sending follow-up emails and call a lawyer.

The Three Claims Every Business Owner Should Understand

Before you can decide whether to sue, you need to know which cause of action fits your situation. Missouri law offers several paths for recovering unpaid invoices, and they are not interchangeable.

Open Account

An "action on account" is the most common vehicle for recovering unpaid invoices. It's a contract-based claim, and the elements are straightforward.

As the court summarized in Helmtec Industries, Inc. v. Motorcycle Stuff, Inc., 857 S.W.2d 334 (Mo. App. 1993):

"Sufficiency of proof depends upon the showing of an offer, an acceptance, and consideration between the parties, as well as the correctness of the account and the reasonableness of the charges. Accordingly, plaintiff must prove that 1) defendant requested plaintiff to furnish merchandise or services, 2) plaintiff accepted defendant's offer by furnishing such merchandise or services, and 3) the charges were reasonable."

Helmtec sold motorcycle helmets to Motorcycle Stuff for several years under an oral agreement. When Motorcycle Stuff fell behind, Helmtec sent a letter and attached a computer-generated account statement showing $166,089.75 in unpaid invoices. The defendant made two payments — $78,063.60 and $64,642.45 — but nothing after that. Helmtec's comptroller testified about the invoices, how the accounting system worked, what payments had been received, and what remained unpaid.

The trial court granted a directed verdict for the defendant, reasoning that Helmtec hadn't submitted a document showing the balance due at the time of trial. The appellate court reversed. The point is worth understanding clearly: you do not need a single, final "balance due" document to prove an open account. You can prove it through a combination of documentary evidence and testimony. A witness who can explain the invoices, describe the accounting system, testify to payments received, and state what remains outstanding is sufficient — even if no single exhibit does all of that work by itself.

Helmtec is also a useful illustration of what acceptable documentation looks like. Helmtec's system generated invoices when goods shipped, credited payments when received, and reconciled accounts monthly. The comptroller could explain how it worked and what each invoice represented. If your invoicing system is that disciplined, you're in good shape. If your records consist of a spreadsheet someone updates when they remember, a collection of text messages, and some invoices you can't find, you have a problem.

Account Stated

An account stated is a different animal. It requires more than proving goods were delivered and charges were reasonable. To establish an account stated, you must prove:

"(1) the parties had prior financial dealings, an open account; (2) the parties reached an agreement as to the amount due and owing on that account; and (3) the debtor acknowledged this obligation and made an unconditional promise to pay."

Scheck Industrial Corporation v. Tarlton Corporation, 435 S.W.3d 705 (Mo. App. 2014). The court added the critical passive-acceptance rule: "In the absence of an express promise to pay, the retention of the account rendered for a reasonable time without objection admits to the account and implies a promise to pay."

This claim requires an actual meeting of the minds on the amount owed. Not just that invoices were sent, but that both parties agreed — explicitly or through failure to object — on the sum.

The Scheck case shows what account stated looks like when it fails. Scheck was a subcontractor on a hydroelectric plant repair project. When its welding work caused cracking in the penstock — the one-mile tunnel that moved water to the turbines — months of expensive repair work followed. Scheck submitted invoices for $553,133.51, arguing the general contractor Tarlton had "acknowledged" the debt because Tarlton hadn't disputed the invoices and had even submitted a claim to the property owner on Scheck's behalf.

The court rejected the account stated claim. Tarlton's project manager had submitted the claim to the owner "based on [Tarlton's] good faith belief that Plaintiff's assertions — that the penstock caused the cracking, not Plaintiff's weldments — were true." Once that turned out to be unsupportable, Tarlton concluded Scheck wasn't owed anything. As the court found, Tarlton "never indicated in correspondence that it would not pay Plaintiff" — but that silence wasn't an implied promise. The emails between the parties "reflect[ed] this same understanding" that payment was contingent on the claim against the owner.

The lesson: submitting invoices without objection is not the same as agreeing they're owed. If the non-payment is tied to a condition — "we'll pay you if the client pays us" — or to an ongoing dispute about the underlying work, you probably don't have an account stated claim. You may still have an open account claim or a breach of contract claim, but those require different proof.

Suit on a Written Promise to Pay

This is where timing can matter enormously. Missouri has two general statutes of limitations for contract claims:

Five years under Section 516.120(1): applies to "all actions upon contracts, obligations or liabilities, express or implied."
Ten years under Section 516.110(1): applies to "an action upon any writing... for the payment of money or property."

The difference can determine whether your case lives or dies.

DiGregorio Food Products, Inc. v. Racanelli, 609 S.W.3d 478 (Mo. 2020), shows exactly how this plays out. DiGregorio had supplied food products to Racanelli's pizza restaurants in St. Louis for roughly two decades. The arrangement was simple: a manager would call in an order, DiGregorio would deliver the next day, and a Racanelli's manager would sign the invoice. Racanelli eventually stopped paying, running up $44,383.85 in unpaid invoices. When he refused to pay, DiGregorio ended the relationship.

DiGregorio filed suit in December 2016 — six to seven years after the invoices had gone unpaid, depending on when you count from. It argued the signed invoices were written promises to pay, triggering the ten-year period. The Missouri Supreme Court disagreed.

"[T]he essence of a promise to pay money is that it is an acknowledgment of an indebtedness, an admission of a debt due and unpaid. What is more, the promise to pay money must arise from the writing's explicit language; extrinsic evidence cannot supply the promise."

The invoices listed dates, items, prices, and quantities. The only thing attributable to Racanelli's side was a manager's signature — and the invoices said nothing about what that signature meant. Compare the invoices to agreements the court had upheld as written promises to pay: a title insurance underwriting agreement that said the company "shall... compensate" at a specified rate; a management service agreement where one party would "pay" the other a percentage of fees collected; and an indemnity bond stating the parties were "indebted" in a specific sum. All of those contained explicit language acknowledging an obligation. A signed delivery receipt doesn't.

DiGregorio's case was barred by the five-year statute. A claim that likely would have won on the merits was lost entirely because of when the lawsuit was filed.

Illustration: The Three Claims Every Business Owner Should Understand

What Can Kill a Good Invoice Claim

Understanding what you're owed is only part of the analysis. Several things can undermine an otherwise solid claim.

Defective or Missing Records

The Helmtec court made clear that an account can be proven through oral testimony, documentary evidence, or a combination of both. But it also illustrated what can go wrong with records that aren't carefully kept.

In Glasco Electric Company v. Best Electric Company, 751 S.W.2d 104 (Mo. App. 1988), an electrical materials supplier sought to enforce a mechanic's lien on a nursing home construction project. Glasco's lien was supported by 78 invoices representing about 306 separate items. The problem: Glasco's own credit manager admitted on cross-examination that several invoices were illegible — not just hard to read, but totally unreadable as to both individual item prices and totals.

The court established a clear floor: "At a minimum the account must advise the owner or the public of the total amount due and the nature of the materials furnished. If neither the individual prices nor the totals are legible, or the items supplied are illegible, the account is insufficient."

The solution wasn't to throw out the whole lien — courts give some latitude for honest mistakes. But the trial court had to go back and specifically exclude the illegible invoices. Some portion of Glasco's claim was simply unenforceable because the records weren't readable.

The lesson for businesses: your documentation is your case. Invoices should be legible, organized, and matched to deliveries. If you use industry abbreviations or codes (which the court said is permissible under trade usage), you need someone who can explain them. If your accounting system creates a paper trail — orders entered, goods shipped, invoices printed, payments credited — preserve it. If a dispute arises, that trail is often the difference between winning quickly and litigating for years.

Payment Application Problems

Glasco also surfaced a problem that arises in businesses with multiple customer accounts: the question of how payments get applied.

Glasco had multiple accounts for Best Electric — including a project account for the nursing home construction and a personal account backed by a promissory note from Best's owner and wife. When Best made a large payment of $28,069.29 with no instructions on how to apply it, Glasco applied it proportionally across all accounts. Best later claimed he had told Glasco to apply it to the personal note, not the project account.

The court articulated the governing rule:

When a debtor owes on multiple accounts and makes a partial payment, the debtor has the first right to specify where the payment goes. If the debtor gives no direction, the creditor can apply the payment however it chooses to protect its interests. The critical exception: if the creditor knows or should know that the payment comes from a third-party source earmarked for a particular account, it must apply the payment in a way that protects that third party.

Because Glasco's witness couldn't recall the conversation Best claimed happened, and nothing in the record proved Glasco knew the source of the funds, the trial court ruled for Glasco — and the appellate court affirmed. But the case illustrates a real risk: if you have customers with multiple accounts and payments come in without remittance instructions, how you apply those payments can affect which invoices remain unpaid, which accounts are current, and — in a construction context — which lien claims survive.

Have a written policy. Apply payments with documentation. When a customer pays and you're unclear on their intent, ask — and get the answer in writing.

The Parol Evidence Problem

Empire Gas Corporation v. UPG, Inc., 781 S.W.2d 148 (Mo. App. 1989), is a dispute between two large propane companies, but its lesson scales directly to any business relationship where the parties have a written agreement and one side claims there was an additional oral understanding.

Empire Gas bought propane from UPG under six written contracts. The contracts said UPG could revise the price for Empire's "customer category" from time to time. But Empire had received a letter before signing saying the price would be "a two cent per gallon discount from UPG's established price." When UPG cut the discount to half a cent, Empire sued for breach — arguing the letter fixed the discount permanently.

The court held the letter was inadmissible to contradict the written contracts:

"Such parties should be held to the terms of their written contract whenever it is reasonable to do so, as it is incumbent upon courts to uphold the dignity of a contract whenever possible by preventing parol evidence from being used to negate the terms of written contracts."

Empire lost a $4.25 million jury verdict because its entire theory of the case was built on a pre-contract letter that contradicted the signed agreement. The signed contracts gave UPG the right to revise the discount. The letter — sent before signing, not incorporated into the contracts, and contradictory to their plain language — couldn't change that.

If you have a business relationship where important terms were agreed to verbally, in emails, or in letters outside the formal contract, understand that those understandings may be unenforceable against a well-drafted written agreement. The time to protect informal agreements is before signing — by building them into the written contract. Once the contract is signed, the document controls.

When the Work Is Disputed: The Workmanlike Performance Problem

One of the most common defenses to an unpaid invoice claim in service and construction businesses is: "We didn't pay because the work wasn't done right."

Missouri law requires that in a breach of contract claim for services or construction, the party claiming payment must prove its work was performed "in a good and workmanlike manner." Scheck Industrial, 435 S.W.3d at 723. "Workmanlike in this context is defined as 'work which is completed in a skillful manner and is non-defective.'"

Scheck Industrial shows what happens when this defense is well-founded. Scheck's welders worked on T-1 steel in the lower portion of Ameren's penstock using a welding procedure designed for a different type of steel. They didn't investigate the steel type before beginning; their quality control consultant never reviewed the project drawings; and once cracking appeared, two subsequent remediation attempts also produced cracks. An independent metallurgical firm ultimately confirmed the cracking was caused by Scheck's improper welding process.

Scheck argued that Tarlton had "waived" any complaint about workmanship by initially directing the welding to continue and by submitting a claim to Ameren on Scheck's behalf. The court rejected both arguments. Continuing work when the parties believed the cracking was isolated isn't acceptance of defective work. Submitting a claim to the owner based on Scheck's own representations — which later proved scientifically unsupportable — isn't ratification. Tarlton stopped the work as soon as the problem became clear, hired outside experts, and directed Scheck to fix it. That's not waiver.

The contrast with Custom Construction Solutions, LLC v. B&P Construction, ED111253 (Mo. App. Nov. 28, 2023), is instructive. In that case involving the Railway Exchange Building project in downtown St. Louis, HH St. Louis refused to pay multiple contractors and architects, and argued they hadn't proven workmanlike performance. The court affirmed judgment for the contractors on this point. Cannon's vice president testified that no one ever told him the architectural work was "insufficient or improper or incomplete." HH St. Louis's own authorized representative confirmed Geotechnology's work was fully performed in accordance with the contract and agreed Geotechnology "should be paid." For Concrete Strategies, neither HH St. Louis nor B&P Construction had ever sent written notice that the work failed to meet the workmanlike standard — and they'd paid some invoices, which the court used as evidence of acceptance.

The pattern is clear: if you've been accepting work, making payments, and raising no objection in writing, a late-breaking "the work was defective" defense is going to have a hard time.

For businesses on the service-provider side, this means: document acceptance. Get signoffs on deliverables. Keep records of payments made — both because they're evidence of your performance and because they create a record the other side can't easily contradict when the dispute arises.

Custom Construction also illustrates the importance of matching your lien to your actual work. Custom Construction filed liens against the Railway Exchange Building, the garage, and the surface parking lot. The evidence at trial showed it had only worked on the garage. The liens against the Railway Exchange Building and the parking lot were struck down — even though Custom Construction's underlying claim was otherwise valid.

This is a good moment to pause on a practical point. If you're reading this because you have invoices that aren't getting paid and you're deciding whether to escalate, the single most useful thing you can do right now is pull together your documentation — every invoice, every delivery receipt, every email about payment, every record of what was accepted and what was paid. That documentation review is usually the first thing we do in a client consultation, and it almost always shapes the strategy. If you can't get your records organized before calling, that's fine — but the sooner they're in order, the faster we can help you understand what you have.

The Mechanic's Lien: Your Most Powerful Tool in Construction and Real Estate Improvement

If your business provides labor, materials, or professional services for construction or improvement of real property, you have access to a remedy more powerful than an ordinary breach of contract claim: the mechanic's lien.

What It Is and How It Works

Missouri's mechanic's lien statute, Section 429.010, gives contractors, subcontractors, materialmen, and professional service providers who aren't paid for work on real property the right to file a lien against the property itself. The lien can then be enforced through a judicial action that may result in the property being sold to satisfy the debt.

The courts are consistent about one key principle: lien statutes are remedial and should be "liberally construed so as to effectuate their object and purpose and protect the claims of the mechanics and materialmen." Custom Construction, citing Midwest Floor Co. v. Miceli Dev. Co., 304 S.W.3d 243 (Mo. App. 2009). "Reasonable and substantial compliance with the statute suffices."

That liberal construction is important — but it has limits. The cases below illustrate both the power of the mechanic's lien and the ways it can be lost.

The "Just and True Account" Requirement

Section 429.080 requires a lien statement to contain "a just and true account of the demand due" and "a true description of the property." Glasco Electric worked through both requirements in detail.

On the account description, the court held that trade abbreviations and codes used in the industry are acceptable — an experienced electrician reading Glasco's invoices would understand that "1 TW CONDUIT--EMT" means a one-inch thin-wall metal conduit. Courts have consistently allowed this since the late 1800s. The test is whether the description "fairly apprises the owner and the public of the nature and the amount of the demand," considered as a whole.

But illegible invoices are a different matter. If a court can't read the prices or the item descriptions, the lien for those invoices fails — even if the contractor genuinely provided the materials. Keep copies. Make sure your submitted lien statement contains legible photocopies of every invoice it references.

On the property description, Custom Construction added a useful reminder. Concrete Strategies's lien against the Railway Exchange Building used the address "612 Olive Street" — while the building spans 611–615 Olive Street — and the legal description in the filing actually described the garage. But attached invoices clearly identified work on the Railway Exchange Building, and the court found that someone familiar with the locality would be able to identify the property. The lien survived. Courts apply a practical, purpose-focused test: can the right people figure out what property is being claimed against?

Notice Requirements

Section 429.100 requires that anyone other than the original contractor who wants to claim a mechanic's lien must give the owner ten days' written notice before filing. This notice must identify the claim, the amount, and who it's owed by.

Custom Construction raised a wrinkle: Concrete Strategies sent its first lien notice to HH St. Louis "in care of Spinnaker St. Louis, LLC" — a management company. HH St. Louis argued Spinnaker wasn't authorized to receive lien notices.

The court applied agency law. The authorized representative of HH St. Louis had told Concrete Strategies to send invoices to Spinnaker, represented he was acting for HH St. Louis, and HH St. Louis's principal had been fully aware of this arrangement without correcting it. Spinnaker therefore had apparent authority to receive lien notices on HH St. Louis's behalf.

The practical point: identify the right owner and the right address early. When you start a construction project, confirm who owns the property and where notice should be sent. Sending notice to the wrong party — or a party that turns out not to have authority — can invalidate your lien.

Lien Priority: Beating the Bank

One of the most powerful and often underutilized aspects of mechanic's liens is priority. Under Section 429.050, a mechanic's lien can attach to improvements "in preference to any prior lien." Under Section 429.060, the lien is preferred to all other encumbrances — including prior-recorded mortgages and deeds of trust — if it arises from a project that commenced before the mortgage was recorded.

Even when a deed of trust predates construction, a lender who knows its loan will fund construction work can waive its priority. Custom Construction is the clearest recent example. Gamma had recorded its deed of trust in February 2017, before any of the construction work began. Normally, that would give Gamma's lien priority over all later mechanic's liens. But the loan agreement was explicitly called a "construction loan agreement." HH St. Louis could only access funds by submitting draw requests that itemized invoices, bills, and receipts for construction work. Gamma approved and controlled those disbursements. The contract even required HH St. Louis to provide "a vendor payee listing showing the name and amount currently due each party... for labor, material, and/or services."

As the court put it:

"A lender who knows and contemplates that mechanic's liens and materialmen's liens can arise from a construction project for which the loan is being made waives the claim of priority of its deed of trust as to the mechanic's lien."

Gamma's deed of trust was subordinated to the mechanic's liens of Custom Construction, Cannon, and Concrete Strategies — even though Gamma recorded first. The lien claimants went to the front of the line ahead of the bank.

For contractors and subcontractors: if you're working on a project funded by a construction loan, your mechanic's lien may have priority over the lender's security interest even if the lender recorded first. This can be the difference between getting paid in a foreclosure and getting nothing.

For lenders, property owners, and developers: understand that funding construction through a controlled disbursement process is evidence of waiver. A lender that actively manages construction draws, reviews invoices, and approves subcontractor payments will have a hard time arguing it didn't know its loan would generate lien exposure.

The Joinder Requirement

Glasco Electric raises one more mechanic's lien trap. Section 429.190 says that parties not made defendants in a lien enforcement action "shall not be bound by any such proceedings." If you want your lien to have priority over a particular encumbrancer, that encumbrancer must be joined as a party. If it's not joined, the lien might still be valid against parties who were joined — but the lien won't affect the missing party's interest.

In Glasco, the bond trustee — Mercantile Trust Company — was not joined as a defendant. Glasco's lien was enforceable against the property owner, the mortgage trustee, and the Authority, all of whom were parties. But as to Mercantile and the bondholders it represented, the lien was ineffective. Glasco couldn't obtain priority over the bond issue because the entity that held the bond-related interest wasn't in the case.

If you're enforcing a mechanic's lien against a property that has multiple liens, encumbrances, or secured interests, get all of them in the lawsuit. Missing a necessary party may result in your lien being unenforceable against the very interest you most need to overcome.

When the PPA Gives You More Than Your Invoices

Custom Construction introduced a remedy that commercial clients sometimes don't know exists: Missouri's Private Prompt Payment Act, Section 431.180.

The PPA applies to "all persons who enter into a contract for private design or construction work." If you haven't been paid in accordance with the contract terms, you can bring an action and the court may award, in addition to your damages:

Interest at up to 1.5% per month from the date payment was due
Reasonable attorneys' fees to the prevailing party

That's not a guarantee — the statute uses "may," giving the court discretion. But in Custom Construction, the court affirmed attorneys' fee awards to Concrete Strategies, Cannon, and B&P Construction under the PPA. HH St. Louis's failure to make scheduled payments under the construction contracts triggered the statute, and the trial court found the fees reasonable and necessary.

For commercial clients in construction and design, this means: if your contract qualifies as a "private design or construction" contract and you aren't paid on time, your potential recovery isn't just the unpaid invoices. It includes above-market interest and — potentially — full reimbursement of the lawyers you had to hire to get paid. That shifts the calculus on whether suing is worth it.

Illustration: When the PPA Gives You More Than Your Invoices

A Practical Framework: When to Call a Lawyer

Based on the cases above, here are the situations that most clearly signal it's time to stop waiting and get legal counsel involved.

The statute of limitations is approaching. DiGregorio lost an entire case because it filed too late. Missouri's general contract limitations period is five years. If your unpaid invoices are getting close to that mark, don't wait. Even if the relationship feels like it might still resolve informally, file a lawsuit (or at least get legal advice about timing) before the clock runs out. You can always settle a lawsuit; you can't un-expire a limitations period.

The non-payer is disputing the work, not just the timing. If a customer is saying the work was defective or the invoices are wrong — not just "we'll pay next week" — that's a different dispute requiring a different analysis. Scheck Industrial and Custom Construction both illustrate how workmanlike performance gets litigated. Get counsel involved before you've made representations about the work that could undermine your position.

The amounts are substantial. The Empire Gas case was worth millions; Scheck Industrial was $553,000; Custom Construction involved multiple liens totaling millions. But even the smaller cases — Helmtec's $23,000, DiGregorio's $44,000 — represent amounts where the cost of hiring a lawyer is far smaller than the cost of not getting paid. The general rule: if the unpaid amount is large enough to materially affect your business, it's large enough to warrant legal representation.

You're in construction and haven't filed a lien yet. Missouri's mechanic's lien statute has short deadlines. Original contractors have six months from completion of the work to file a lien; subcontractors and materialmen have six months from the date they last provided labor or materials. Miss those deadlines and your lien right is gone — leaving you with only an ordinary contract claim against whoever you contracted with directly (not the property owner). If you're in a construction dispute and you haven't filed your lien, find out immediately whether you still can.

The other side has a lender or a mortgage on the property. The Glasco and Custom Construction cases both show that lien priority — deciding who gets paid first if the property is sold — requires getting the right parties into the case. This is not a DIY analysis.

You have multiple accounts and payment application is getting complicated. If a customer has paid some invoices but not others, and the non-payment is starting to look intentional, the Glasco payment-application principles become relevant. Which account is current? Which invoices are actually unpaid? Has the customer tried to direct payments away from the invoices you care most about? This analysis requires careful record work and often legal guidance.

The customer has given you a written promise to pay that's more than five years old. Read DiGregorio carefully. If you have documents that might constitute a written promise to pay, the ten-year period may apply. But courts require explicit language — not just a signature on a delivery receipt. Get a lawyer to evaluate your documents before assuming you have more time than you do.

The Bottom Line

Unpaid invoices are not just a collection problem — they're a legal problem with real procedural rules, real deadlines, and real consequences for how well you've documented your work and managed your accounts. The businesses that recover what they're owed are the ones that kept clean records, understood their claims, filed on time, and got counsel involved before the situation was irreversible.

If your invoices aren't being paid and you're not sure whether or when to escalate, the right time to have that conversation with a lawyer is before you've missed a deadline, before you've made representations you can't walk back, and before the pattern of non-payment becomes a pattern of loss.

Our attorneys work with commercial clients — from small businesses chasing a few thousand dollars to contractors and subcontractors navigating complex construction lien priority disputes — to evaluate claims, build documentation strategies, and pursue recovery efficiently. If you have a collection problem that isn't resolving on its own, let's talk about whether it makes sense to make it a legal problem for the other side.

This article is for informational purposes only and does not constitute legal advice. For advice specific to your situation, please consult a qualified attorney.