Can I invoice clients without a signed contract in the US?

Understanding the Question: Invoicing Without a Signed Contract

If you run a service business, freelance operation, agency, or small company in the United States, you’ve probably faced the awkward moment where work is underway (or already finished) but the “official contract” never got signed. Maybe the client agreed over email, maybe you had a phone call and started quickly to meet a deadline, or maybe the relationship began casually and evolved into a bigger project. Then comes the practical question: can you invoice clients without a signed contract in the US?

In most cases, yes—you can send an invoice even if there isn’t a signed contract. But whether you can successfully collect payment if the client disputes it is a different issue. Invoicing is a billing action; enforceability depends on whether a valid agreement exists and whether you can prove the essential terms. The good news is that US law often recognizes agreements that are not “signed contracts” in the traditional sense, including oral contracts and implied contracts. The less fun news is that proving the agreement is harder without clear documentation, and certain types of deals are legally required to be in writing.

This article breaks down how invoicing works without a signed contract, what makes an agreement enforceable, when a writing is required, how disputes typically play out, and what you can do to protect your business. It also includes practical workflow advice so you can confidently invoice through invoice24, your free invoice app, even when paperwork is incomplete.

Invoicing vs. Contract: They Are Not the Same Thing

An invoice is a request for payment. It typically lists what you delivered (goods or services), the price, the due date, payment methods, tax (if applicable), and any payment terms like late fees. A contract, on the other hand, is the agreement that sets the rules of the deal: scope, price, timeline, responsibilities, ownership rights, confidentiality, dispute resolution, and more.

You can absolutely create and send an invoice without a signed contract because invoicing is not legally restricted to contract situations. People invoice for many reasons: after a one-time repair, after consulting hours, for an event deposit, for reimbursable expenses, or for recurring monthly services. The invoice itself can even serve as part of the evidence of the agreement if a dispute occurs, especially when combined with emails, proposals, text messages, purchase orders, delivery notes, or records showing the client accepted your work.

However, an invoice alone does not automatically create a binding obligation if the client never agreed to the terms. That’s why your best approach is to treat the invoice as one piece of a larger documentation strategy rather than as the only proof that payment is owed.

Are Unsigned Agreements Ever Enforceable in the US?

Yes. A signed document is not the only way to form an enforceable contract in the US. Most contracts can be formed as long as the key legal elements are present. Generally, these elements include:

Offer: One party proposes specific terms (for example: “I will design your logo for $800 with two rounds of revisions”).

Acceptance: The other party agrees to those terms (“Sounds good, please start” or behavior that clearly indicates agreement).

Consideration: Each side gives something of value (you provide services; the client pays money).

Mutual intent: Both sides intend to enter a business arrangement, not a casual or purely social promise.

Definiteness: The essential terms are reasonably clear (what work, what price or how price is calculated, and the general timeframe).

If those elements exist, a contract may be enforceable even if nothing was signed. Depending on the situation, the contract might be oral, written but unsigned, or implied by conduct.

Common Types of Non-Signed “Contracts” That Still Count

Oral Agreements

Oral contracts are often valid for many kinds of services. If you and a client agree by phone that you’ll do a job for a certain price, and you do it, that can be an enforceable agreement. The challenge is proof: if the client later denies the agreement or disputes the price, you will need evidence. That evidence might be follow-up emails, calendar invites, text confirmations, work logs, or partial payments.

Agreements Formed Through Email or Text

Email chains and text messages frequently contain the offer-and-acceptance sequence needed for a contract. A client saying “Approved—go ahead” after receiving your proposal can be extremely important. Even if you never exchanged a formal signature, clear written acceptance can be enough to show there was a deal.

Implied-in-Fact Contracts

Sometimes nobody ever clearly says, “I accept your offer,” but the client’s actions show agreement. For example, a client asks you to begin work, gives you access to systems, reviews drafts, requests revisions, and then uses the final deliverables. This pattern can support an implied-in-fact contract: an agreement inferred from behavior rather than from explicit words.

Course of Dealing With Repeat Clients

If you’ve worked with the same client for months or years, past behavior can support the idea that the client understood your pricing and billing method. While you should still document each project, a consistent history of similar invoices being paid helps establish expectations.

When a Signed Writing May Be Required

Although many agreements can exist without signatures, certain types of transactions must be in writing to be enforceable due to legal rules often referred to as “statute of frauds” requirements. These rules vary by state, but common categories that often require a written contract include:

Agreements that cannot be performed within one year: If the deal, by its terms, is impossible to complete within one year, many states require a writing.

Real estate transactions: Deals involving the sale of land or interests in land typically require a written agreement.

Sale of goods over a threshold amount: Under the Uniform Commercial Code (UCC), contracts for the sale of goods over a certain dollar amount generally require a writing. (Many businesses are service-based, but if you sell products, this matters.)

Surety agreements: Promises to pay another person’s debt often require a writing.

Some state-specific categories: Certain consumer contracts, home improvement agreements, or specific regulated services can require written disclosures or contracts.

This doesn’t mean you can’t invoice without a signed contract in those situations, but it can affect your ability to enforce payment if the client refuses and the legal rules say the agreement must be written. When in doubt, it’s safer to get something in writing—even a simple written confirmation—before starting.

Can You Collect Payment Without a Signed Contract?

Many businesses successfully collect payment every day without signed contracts because payment often happens through normal commercial practice: the client knows the work was done, values the relationship, and pays. Problems arise when there’s a dispute: the client claims the work wasn’t authorized, argues about the scope, says the price wasn’t approved, or raises quality concerns.

In a dispute, the key question becomes: can you prove there was an agreement and what its terms were? Even without a signed contract, you may be able to prove that:

The client requested the work (messages, emails, call notes, tickets, purchase orders).

You performed the work (deliverables, time logs, screenshots, file history, shipping confirmations).

The client accepted the work (approval emails, usage, publication, go-live confirmations, lack of objection after delivery).

The price or rate was communicated (proposal, estimate, rate sheet, prior invoices, message stating the rate).

The client benefited from the work (they used it, sold it, promoted it, or otherwise got value from it).

The more of these points you can document, the more confident you can be sending the invoice and expecting payment—even without signatures.

What If the Client Never Explicitly Approved the Price?

Pricing disputes are one of the biggest risks when there’s no signed contract. A client may say, “I didn’t agree to that amount,” or “I thought it was included,” or “I didn’t approve those extra hours.” If you’re billing hourly, this can get especially messy without clear limits and change approvals.

If you are in this situation, your best strategy is to document pricing as early and clearly as possible. That can include a written estimate, a rate confirmation email, a statement of work, or even a short message that says: “Confirming I’ll proceed at $X/hour with an estimated range of Y–Z hours.” If the client replies “OK” or continues directing you to work, that message becomes powerful evidence.

When it’s already too late and work is completed, you can still invoice, but it’s wise to attach supporting documentation or reference it clearly: “Per our email on [date] approving the project at $____” or “Per our agreed rate of $____/hour.” Avoid sounding accusatory. Keep it factual and businesslike.

Can the Invoice Itself Create an Agreement?

An invoice can help show what you believe the agreement was, and if the client pays it, that payment can be strong evidence that they accepted the terms. But an invoice sent after services are performed is generally not the best way to introduce brand-new terms the client never agreed to—like unexpected late fees, ownership clauses, or new cancellation rules.

That said, invoices can include payment terms, and many businesses do so. The key is consistency and fairness. If you routinely include the same payment terms, communicate them up front, and the client continues to do business with you, those terms are more likely to be treated as part of the commercial relationship.

For practical purposes, you can include clear, reasonable terms on your invoice, such as payment due date, accepted payment methods, and late payment charges where allowed. But for bigger issues—like intellectual property ownership, confidentiality, warranty limits, or arbitration—those should ideally live in a separate agreement or terms document that the client sees before the work begins.

What Happens If the Client Refuses to Pay?

If a client refuses to pay and you don’t have a signed contract, your next steps depend on the amount owed, the strength of your documentation, and the value of the relationship. Typically, escalation follows a path like this:

1) Friendly Reminder and Clarification

Many non-payments are administrative: invoices get lost, approvals are delayed, or the wrong person was billed. A polite reminder often solves it. Provide the invoice number, due date, and a link to pay. invoice24 is ideal for this because clients can view the invoice, download it, and pay using the methods you offer.

2) Provide Supporting Records

If the client disputes, respond with documentation: the proposal, the email approval, a summary of hours, delivery confirmation, or a change request trail. The goal is to make it easy for them to see the chain of events without turning the conversation into a fight.

3) Final Demand and Notice of Next Steps

If reminders fail, a more formal “final notice” may be appropriate. Keep it professional. Reference what was delivered, the agreed price or rate, and a clear deadline to pay before you pursue other remedies.

4) Collections, Mediation, or Small Claims Court

For smaller amounts, small claims court is often a practical option, and the judge will look for evidence of an agreement and performance. For larger amounts, you may consider a lawyer, formal demand letter, mediation, arbitration (if agreed), or a collection agency. Your chance of success improves dramatically if you have organized records: dated communications, invoices, proof of delivery, and proof the client benefited.

Key Legal Theories That Can Support Payment Without a Signed Contract

If there’s no enforceable written contract, there may still be legal paths that support payment. While the specifics vary by state and case, common concepts include:

Breach of Contract (Based on Oral/Written/Implied Agreement)

If you can prove an agreement existed—even without signatures—you may claim the client breached by not paying. Evidence matters more than formalities.

Quantum Meruit / Unjust Enrichment

When someone receives and benefits from services but doesn’t pay, courts may order payment based on the reasonable value of the work to prevent unjust enrichment. This is especially relevant when the scope wasn’t perfectly defined but the benefit is clear.

Promissory Estoppel

If the client made a promise you reasonably relied on (like “Go ahead, we’ll pay”) and you incurred costs or spent time based on that promise, some states allow recovery to avoid unfairness.

You don’t need to use these legal labels in everyday billing conversations. Just know that the legal system can recognize fairness and commercial reality, particularly where a client requested and accepted work.

Practical Risks of Invoicing Without a Signed Contract

Even though it’s common to invoice without a signed contract, the risks increase when:

The project is large or complex: More room for misunderstanding about scope and deliverables.

There are multiple stakeholders: Someone later says, “I didn’t authorize this.”

Scope changes frequently: Extra work becomes difficult to justify without written change approvals.

The work is subjective: Creative services can trigger “I’m not satisfied” disputes.

Payment depends on outcomes: Performance marketing or sales-based arrangements need tight definitions.

There is intellectual property at stake: Ownership and usage rights should be crystal clear.

There are compliance requirements: Certain industries require written agreements, disclosures, or specific contract terms.

If any of these apply, sending the invoice is still allowed, but you should strengthen your documentation process immediately for future work.

How to Protect Yourself When There Is No Signed Contract

If you’re already in a “no signature” situation, you can still reduce risk by tightening your process around communication and billing. Here are practical steps that help in real-world disputes:

Send a Written Confirmation Before You Start (Even If It’s Short)

A simple email can act like a mini-contract: “Confirming I’ll provide X service for $Y, delivery by Z date, payable net 7.” Ask the client to reply “Approved.” This is fast, not intimidating, and creates a clean record.

Use Estimates and Convert Them Into Invoices

When the scope is uncertain, provide an estimate with assumptions and a range. Then convert it to an invoice when the work is complete. This makes pricing feel expected rather than surprising. You can do this smoothly in invoice24 by creating an estimate-style invoice or a detailed invoice with line items and notes.

Track Work and Deliverables

Keep time logs, project notes, version history, and delivery confirmations. Even basic documentation can be persuasive: “Delivered final files on [date] via [method].”

Get Change Approvals in Writing

Scope creep is where many billing disputes come from. If the client asks for additional work, reply with a short message that clarifies impact: “Happy to do that—this adds $___ or ___ hours.” Once they confirm, you’re protected.

Invoice Promptly and Consistently

Delays create confusion. Invoice as soon as milestones are completed or on your normal billing schedule. Consistency also trains clients to expect invoices and pay on time.

Use Clear Payment Terms

Put the due date on every invoice and keep terms simple: Net 7, Net 14, or due upon receipt. If you charge late fees, state them clearly and keep them reasonable. invoice24 makes it easy to include these terms automatically so you don’t forget.

Make It Easy to Pay

Many “non-payments” are actually “friction payments.” If the client needs to request a check vendor setup, find bank details, or ask for the invoice again, your cash flow slows. Use invoice24 to offer easy payment options, clear totals, downloadable invoices, and quick resend reminders.

Should You Stop Work Until There’s a Signed Contract?

For small, low-risk jobs with trusted repeat clients, you may choose to proceed based on email confirmation and an invoice. For higher-value or higher-risk projects, it’s generally smart to pause until you have at least a written approval of scope and price. This doesn’t always need to be a formal 10-page contract. A short statement of work and acceptance email can be enough to reduce risk dramatically.

A practical middle path is to require a deposit invoice before beginning. If the client pays the deposit, that payment is strong evidence they agreed to proceed. It also reduces the risk of doing lots of work without any cash received.

Deposits, Retainers, and Milestone Invoices Without Signatures

Deposits and retainers are common ways to manage risk and cash flow. You can invoice for them even without a signed contract, but clarity matters. Your invoice should specify exactly what the payment represents:

Deposit: An upfront payment applied to the final total.

Retainer: A payment that reserves capacity and may be applied to future work, depending on the agreement.

Milestone payment: Payment due after a defined deliverable is completed.

Make sure the invoice notes explain whether the payment is refundable, how it will be applied, and what triggers the next invoice. If you’re not using a formal contract, these invoice notes become extra important. invoice24 lets you include structured line items and notes so you can document these details right on the invoice.

Special Considerations for Freelancers and Agencies

Freelancers and agencies often start work quickly to meet deadlines. That’s normal, but it increases the chance of “we never agreed” problems. A few extra precautions can make invoicing much safer:

Define scope with bullet points: Even a short list prevents misunderstandings.

Define revisions: Specify how many rounds are included and what counts as out-of-scope.

Define deliverable formats: Files, access, training sessions, documentation—list it.

Define timeline dependencies: If client delays feedback, deadlines shift.

Define ownership transfer timing: Many creatives transfer rights upon full payment.

You can reflect many of these points in the invoice description or a short attached scope document referenced by the invoice.

Special Considerations for Contractors, Trades, and Local Services

Trades and local services often operate on work orders, estimates, and invoices rather than formal contracts. In many states, certain home improvement projects require specific written agreements or disclosures, and those rules can be strict. Even when no special rule applies, it’s still wise to document:

The address and date of service so there’s no confusion about where the work occurred.

Materials and labor breakdown to show how the total was calculated.

Before/after photos for proof of work.

Customer approvals for change orders or added items.

With invoice24, you can create detailed line items, attach notes about materials, and keep invoices organized so you can quickly locate them if questions arise.

What to Include on an Invoice When There’s No Signed Contract

If you are invoicing without a signed contract, the invoice should be as clear as possible. Consider including:

Client information: Legal name, business name, address, and contact person.

Your business information: Name, address, and any required business identifiers.

Invoice number and date: For tracking and easy reference.

Detailed description of services: What you did, when you did it, and the scope.

Quantity and rate: Hours, unit price, flat fee, or milestone amounts.

Supporting notes: “Per approval on [date]” or “Per estimate provided on [date].”

Payment terms: Due date, accepted payment methods, and late fee policy if used.

Taxes: If applicable, show them clearly and accurately.

Balance due: Clear total and any deposits already paid.

invoice24 is designed to handle these fundamentals cleanly, so your invoices look professional and contain the details clients (and sometimes courts) want to see.

Can You Add Late Fees or Interest Without a Signed Contract?

Many businesses include late fees on invoices, but enforcing them can be harder if the client never agreed to them in advance. The best practice is to communicate late fees before work begins—ideally in a short written agreement or at least in a written confirmation message. If you introduce late fees only after the fact, a client may argue they never agreed to those charges.

A practical approach is to keep your late fee policy modest and standardized, and to include it consistently on invoices and reminders. Even better, send a pre-work message that mentions payment terms and late fees in plain language. invoice24 can help by automatically adding your default payment terms to every invoice so you don’t miss it.

What About Charging for Collections Costs or Attorney Fees?

Recovering collection costs or attorney fees usually requires an agreement or a specific legal basis. If you don’t have a signed contract with a fee-shifting clause, it can be difficult to demand those costs from the client. That’s one reason written agreements matter for higher-value work. Without them, your best leverage is strong documentation of the debt and a clear, professional collection process.

How Clients Typically React to Invoices Without Signed Contracts

Most clients will not care whether a contract was signed if they requested the work and received what they wanted. They care that the invoice is accurate, clear, and easy to process. Problems tend to happen when:

The invoice surprises them: Unexpected amounts, unclear line items, or unapproved add-ons.

The approver changes: A new manager reviews the invoice and questions it.

Budgets tighten: Payment is delayed and excuses appear.

The relationship sours: Quality concerns or communication issues turn into payment disputes.

The more professional and organized your invoicing process is, the less room there is for a client to stall or dispute. A well-structured invoice in invoice24 supports that professionalism.

Best Practices Going Forward: Preventing the “No Signed Contract” Problem

If you want to keep moving fast without losing protection, build a lightweight system that creates enforceable clarity without slowing sales. Here’s a practical workflow:

Step 1: Send a Simple Scope and Price Summary

Before starting, send a short message: scope bullets, price, timeline, and payment terms. Ask for a reply confirming approval.

Step 2: Invoice a Deposit (Optional but Powerful)

Send a deposit invoice through invoice24. Once paid, you have strong evidence of agreement and commitment.

Step 3: Document Changes

When scope changes, confirm the cost impact in writing and keep the record in the same email thread when possible.

Step 4: Invoice Promptly With Details

Invoice at milestones or upon completion. Use line items, descriptions, and a clear due date.

Step 5: Follow Up on Overdue Invoices

Use polite reminders, then firmer notices if needed. Keep communications professional and factual.

Final Takeaway

So, can you invoice clients without a signed contract in the US? Yes, you can—and many businesses do. A signed contract is not always required to form an enforceable agreement, and payment obligations can arise from oral agreements, email acceptances, and even conduct that shows mutual understanding.

But the absence of a signature increases the risk of disputes and makes proof more important. The safer your documentation—clear scope, clear price, records of approval, proof of delivery—the more confidently you can invoice and the more likely you are to collect if something goes wrong.

With invoice24, you can send professional invoices that clearly document what you provided, how the total was calculated, and when payment is due. Combine that with simple written confirmations and consistent processes, and you can keep business moving—even when a formal contract isn’t signed yet.