They never objected. That is evidence.

NY COMMON LAW · ACCOUNT STATED

What an account stated is.

An account stated is an agreement between parties to an account that the balance shown is correct and owed. The agreement does not have to be spoken or signed. New York courts have long held that it can be implied from conduct: one side renders a statement of the account, the other side receives it and keeps it for a reasonable time without objecting, and the law infers assent to the balance. A partial payment on the statement supports the same inference, because paying part of a bill you dispute is not what people normally do.

The doctrine is a creature of New York common law rather than a statute, so you will not find a section number for it. What you will find is a consistent line of decisions treating a customer's silence after receiving invoices as evidence that the amount is owed. That is the whole point: it converts the debtor's inaction into your proof.

The three things you have to show.

Stripped down, an account stated claim has three parts:

1. You rendered a statement. An invoice, a statement of account, a ledger summary, anything that sets out the balance with enough detail that the recipient could check it.
2. They received it. Not necessarily signed for, but sent to the right business at the right address or email, in the way you and the customer normally communicated. A regular course of emailing invoices to the customer's accounts-payable address is typically enough.
3. They kept it without objecting within a reasonable time, or they paid part of it. Silence for months after receipt is the classic pattern. A partial payment without a reservation of rights is even better.

Notice what is missing. You do not have to prove the contract terms line by line or litigate the value of every hour. Those issues belong to a breach of contract claim, which you will usually plead alongside account stated. Account stated is the claim that says: whatever the deal was, you agreed to this number by not disputing it.

What “reasonable time” and “objection” mean in practice.

There is no fixed number of days. Courts look at the relationship and the industry. Between businesses that exchange invoices routinely, a few months of silence is generally treated as unreasonable delay in objecting. A single invoice held for three weeks during a busy quarter is a closer call. The longer the silence, and the more invoices that piled up without a word, the stronger the claim.

An objection has to be an actual objection to the account. “We will pay when cash flow improves” is not an objection; it is an acknowledgment. “Can you send the backup?” is a request, not a dispute. A written statement that specific charges are wrong, or that the work was not done, is an objection, and if it came within a reasonable time it defeats the inference of assent for the disputed portion. Oral objections count too, but they are harder to prove, which is one reason debtors who were truly unhappy usually write it down.

What account stated does not do.

Be honest with yourself about the limits, because a court will be.

• It does not create a debt that never existed. There must be an underlying relationship in which the debtor agreed to pay for something. You cannot invoice a stranger, wait six months, and claim an account stated.
• It does not survive a timely dispute. If your customer rejected the deliverables or contested the charges in writing when they arrived, account stated is off the table for the contested amounts. You are back to proving breach of contract. That is the disputed-work screen we apply before drafting any letter.
• It does not fix a bad address. Invoices sent to a former contact's dead email or a previous office are weak proof of receipt.
• It does not help against a guarantor who never got the statements. Claims against an owner who signed a personal guarantee rest on the guarantee itself.

A worked example.

A Brooklyn marketing agency bills a Long Island manufacturer monthly. Between March and August it sends six invoices totaling $31,500, each emailed to the manufacturer's accounts-payable address, where every earlier invoice had been paid without issue. The manufacturer pays the March invoice in full and sends $5,000 toward April with the note “partial, rest next month.” Then nothing. The agency's emails in September and October go unanswered. In November the manufacturer's new controller writes that the agency's work “was never what we needed.”

On these facts, the agency has a strong account stated claim for the outstanding $22,000. The invoices went to the same address that had always worked. They sat for three to eight months. The partial April payment acknowledges the account. The first “objection” arrived only after collection pressure began and is vague about which charges are wrong. The controller can still try to argue the merits in a breach of contract defense, but the account stated claim means the agency is not starting from zero, and the debtor is the one explaining why a company that pays in part and says nothing for half a year now disputes everything.

What a demand letter does here.

A well-built demand letter is an account stated machine. Ours does the following, deliberately:

• Restates the account. The letter attaches a current statement listing each invoice, date, amount, payments received, and balance. That is itself a fresh rendering of the account.
• Documents the silence. It recites when each invoice was sent, to whom, and that no objection was ever received. Putting the history in a dated attorney letter preserves it.
• Invites an objection, in writing, by a deadline. This sounds counterintuitive. It is not. If the debtor objects now, you learn the actual dispute before filing anything. If the debtor stays silent again, after an attorney's letter expressly asked for any objection, the inference of assent is about as strong as it gets.
• Adds interest. The balance is stated as principal plus 9% statutory interest from each due date, computed per New York's late payment interest rules.
• Goes by mail and email, to the entity's registered address and the working accounts-payable contact, so receipt is not a question later.

The letter is a flat fee. It is the cheapest way to both pressure payment and improve the case if payment does not come.

If you end up in court.

Account stated is pleaded alongside breach of contract in nearly every New York commercial collection action. In the commercial claims part, which handles modest business claims quickly, you bring the invoices, the proof they were sent, and the record of silence; see commercial small claims in New York. In a larger Civil Court or Supreme Court case, a clean account stated record is what lets your lawyer move for judgment early rather than slog through a trial on the merits. Either way, the work you do now, sending a statement and noting the non-response, is what you will be standing on later. Whether to file at all is a separate question, covered in demand letter vs. small claims.

Build the record starting today.

• Send a consolidated statement of account to the customer's known accounts-payable email and the entity's registered address.
• Keep the sent emails, delivery confirmations, and any read receipts.
• Save every reply, including the non-committal ones. “We'll get to it” is an admission.
• Record partial payments with dates and any memo text.
• If the customer has gone completely quiet, follow the sequence in when a client ghosts an unpaid invoice.