Skip to main content
Postmarkr

HOW-TO

Demand Letter Template, the Unpaid-Invoice Version, and How to Mail It

A copyable demand letter template and an unpaid-invoice version, how to mail one or several First-Class from a laptop, what to check before you mail (the contract, any statute the lawyer named, the court form), how to set a deadline that survives mailing time, and what to keep in the file.

POSTMARKR6 MIN READ

A demand letter tells the other side who is owed what, why, by what date, and what happens next, and it is signed by the sender or their lawyer. Below is a template for a demand sent on a client's behalf, a shorter version for an unpaid invoice, how to mail one or several First-Class from a laptop, what to check before you mail, how to set a deadline that survives mailing time, and what to keep in the file.

These templates show structure, not legal advice; the lawyer on the matter decides what the letter says. {{double_braces}} marks a merge field you fill for each letter; [square brackets] mark wording you write once. Lines are broken to fit a phone screen; join each paragraph after you paste.

Demand letter template#

Six parts do the work:

  • Parties: who you represent and who owes, at the address the contract or the other side's letterhead names.
  • Basis: what happened, with dates and the contract, invoice or order it rests on.
  • Amount: a figure and how you reached it.
  • Deadline: a calendar date, not "within 10 days."
  • Consequence: the next step the sender intends to take.
  • Signature: name, firm and contact details.
{{date}}

[Via First-Class Mail. List only the methods you use.]

Re: Demand for payment: {{matter}}
Our file: {{our_file_no}}

Dear {{salutation_name}}:

This firm represents {{client_name}} in {{matter}}.
[If the contract or a statute calls for this demand,
name it here.]

What happened: {{basis}}

Amount: {{client_name}} asks you to pay {{amount}}:
{{amount_detail}}.

Please pay, or reply in writing with a proposal, by
{{deadline_date}}. [How to pay: link, address, phone.]

If we have not heard from you by then, {{next_step}}.

Sincerely,

{{sender_name}}
[Firm name, phone, email]

[Enclosures: list them.]
cc: {{client_name}}

Writing for yourself or your own business? Swap the first paragraph for "I am writing about …" and drop the cc line. {{next_step}} is whatever the lawyer or sender has decided to do next, written as a plain sentence. The letter carries no inside address: Postmarkr prints the recipient's address on the page it adds. If you mail it from a post office counter instead, add the recipient's name and address above the salutation. Enclosures ride only with a PDF: a template with fields goes out on its own, so when there is something to enclose, fill the letter in Word and save it with its enclosures as one PDF.

Unpaid-invoice version#

For a business owed money by a customer, the letter is shorter and points at the invoice.

{{date}}

Re: Invoice {{invoice_number}}, due {{due_date}}

Dear {{salutation_name}}:

Invoice {{invoice_number}}, dated {{invoice_date}}, for
{{work_done}}, was due on {{due_date}}. The unpaid
balance is {{amount_due}}.

Please pay {{amount_due}} by {{deadline_date}}
[by pay link, or by check mailed to: address].

If payment has not arrived by then, I intend to
{{next_step}}.

If you have already paid, please tell me the date and
amount so we can match it.

Sincerely,

{{sender_name}}
[Business name, phone, email]

Enclosing the invoice? Put it behind the signed letter in one PDF and send it as one letter. Postmarkr can't include a return envelope or a check, so give a pay link or a mailing address for payment.

How to mail a demand letter#

Postmarkr prints and mails USPS First-Class letters; a one-page black-and-white letter is $2.05 all in, postage included.

  • One letter: save the signed letter as a PDF, enclosures behind it. Upload it, pick a saved contact or type the address (checked for USPS deliverability), approve the preview and total, and pay by card.
  • The template above, with its fields: save it as a Postmarkr letter template and use Bulk Send. A single send refuses a template with merge fields, so upload a CSV with one row: the address columns plus one filled-in column per field. Every field needs a value, up to 512 characters, so a longer account of what happened goes in the template's own text or in a PDF. The same batch takes up to 100 recipients and $1,000 if you are sending the same demand to several people.
  • Several different letters: add up to 10 PDFs to your Cart and check out once.

Each letter is printed the next business day. Its status page shows processing milestones and USPS scan updates when available, and you can download the PDF of exactly what was printed for the file. That record isn't a Certificate of Mailing and doesn't show a USPS-confirmed mailing date.

Postmarkr sends USPS First-Class letters only. It doesn't send Certified Mail, doesn't issue a Certificate of Mailing (PS Form 3817), and can't give you a USPS-confirmed mailing date. If a statute, rule, contract or court order calls for one of these, use a post office counter or a Certified Mail provider. Our guide to Certified Mail alternatives shows what each USPS option records.

Who gets the letter: the party who owes, at the address the contract or their letterhead names. If the other side has a lawyer in the matter, the lawyer on your file tells you whether the letter goes to the party or to counsel; our letter to opposing counsel guide covers the counsel version. More law-office mailing guides live on our law firm mailing hub.

Before you mail: the contract, the statute, the court form#

Three places can name the mail method, the address, or both. Check them in this order, and if one names a method, use exactly that method.

  1. The contract's notices clause. Contracts often say how notices must be sent and where. Read the clause before you choose a mail class.
  2. Any statute the lawyer named. Some laws that call for a demand before suit also say how it must be sent. Ask which law, if any, the demand rests on, and read its own words on sending.
  3. The court's form. Small-claims forms often ask whether you demanded payment before filing, and some court sites publish a sample letter.

Where the official guidance lives:

Set a deadline that leaves room for mailing#

Write a calendar date in the letter, and count backwards from it. A Postmarkr letter is printed the next business day after you pay, and USPS estimates 1–5 days (opens in new tab) for First-Class delivery. A letter paid for on a Thursday can land the following Wednesday, so a deadline ten days out gives the other side less than a week once it arrives. Leave mailing time on both ends: for the letter to arrive, and for a mailed reply or check to come back.

If a contract or statute sets its own waiting period, the lawyer tells you which date starts it. Your job is the record: note the day you paid in the file and keep what the next section lists.

What to keep in the file#

  • The signed letter exactly as mailed, with its enclosures.
  • The contract clause, statute or court form you followed, with the date you read it.
  • The mailing record: for a Postmarkr letter, the PDF of exactly what was printed and its status page; for a counter mailing, the Certified receipt and return receipt, or the Certificate of Mailing.
  • Each reply, payment or call that follows the letter, with its date.

One row in a mail log keeps this together across matters. Our proof-of-mailing guide has a free law firm mail log to download as a CSV or PDF, with a "Deposited by" column where you enter Postmarkr and the Payment ID from your receipt email.

LegalLetters
ready