Official Unpaid Invoice Demand Letter: Template & Legal Collection Rules

Did You Know? You Can Add Statutory Pre-Judgment Interest

Even if your original invoice did not explicitly specify a late fee percentage, every US state authorizes statutory interest on liquidated debts from the date payment was due:

Use our Statutory Interest Calculator to calculate exact daily interest →

Generate an Attorney-Grade Unpaid Invoice Demand in Seconds

Input your invoice numbers, due dates, and principal balance. Our tool formats an official court-ready PDF with statutory interest clauses ready for certified mailing.

[YOUR NAME OR BUSINESS / COMPANY NAME]
[YOUR BUSINESS MAILING ADDRESS]
[CITY, STATE, ZIP]
Phone: [YOUR PHONE NUMBER]
Email: [YOUR BUSINESS EMAIL]
Date: [CURRENT DATE]

VIA USPS CERTIFIED MAIL - RETURN RECEIPT REQUESTED
TRACKING NO: [INSERT 20-DIGIT USPS NUMBER]
AND VIA REGULAR FIRST-CLASS MAIL

To Debtor / Accounts Payable:
[CLIENT CONTACT NAME / TITLE]
[CLIENT COMPANY NAME]
[CLIENT STREET ADDRESS]
[CITY, STATE, ZIP]

RE: FINAL DEMAND FOR IMMEDIATE PAYMENT OF DELINQUENT INVOICE(S) PRIOR TO LEGAL ACTION
OUTSTANDING PRINCIPAL BALANCE: $[PRINCIPAL INVOICE AMOUNT]
STATUTORY PRE-JUDGMENT INTEREST ACCRUED: $[INTEREST AMOUNT]
TOTAL AMOUNT DEMANDED: $[TOTAL AMOUNT DEMANDED]
FINAL COMPLIANCE DEADLINE: [DATE 10 OR 14 CALENDAR DAYS FROM TODAY]

Dear [CLIENT CONTACT NAME],

This letter serves as formal written legal notice and a final demand for payment regarding severely delinquent indebtedness owed by [CLIENT COMPANY NAME] for professional services and goods delivered in full by the undersigned.

FACTUAL BASIS OF INDEBTEDNESS:
1. Pursuant to our binding agreement dated [CONTRACT / STATEMENT OF WORK DATE], Claimant performed all agreed professional services and delivered all final deliverables to your complete satisfaction.
2. Formal Invoice #[INVOICE NUMBER] in the principal amount of $[PRINCIPAL AMOUNT] was tendered on [DATE INVOICE SENT] with contractual payment terms due on [DUE DATE].
3. Despite multiple informal notifications sent on [DATE OF EMAIL 1] and [DATE OF EMAIL 2], and your repeated confirmation of receipt, the account remains delinquent by [NUMBER OF DAYS] days.

ACCOUNTING OF DAMAGES & STATUTORY INTEREST:
Pursuant to the contract terms and the statutory interest laws of the State of [STATE NAME], damages are itemized as follows:
- Principal Outstanding Balance: $[PRINCIPAL AMOUNT]
- Contractual Late Fees / Statutory Interest ([X]% per annum): $[INTEREST AMOUNT]
- Administrative & Certified Notice Delivery Costs: $[MAILING EXPENSES]
- TOTAL LIQUIDATED AMOUNT DEMANDED: $[TOTAL COMBINED AMOUNT]

FINAL COMPLIANCE DEADLINE:
Demand is hereby made that [CLIENT COMPANY NAME] tender full payment of $[TOTAL AMOUNT] within [10 OR 14] calendar days of receipt of this notice, no later than 5:00 PM on [DEADLINE DATE].

Payment Remittance Instructions:
Please remit payment via Wire Transfer, Automated Clearing House (ACH), Cashier's Check, or Corporate Check made payable to "[YOUR BUSINESS NAME]" at the address above.

NOTICE OF INTENDED LITIGATION:
If full payment is not received by the stated deadline, I will immediately file a formal civil complaint against your company in the [LOCAL COUNTY / MUNICIPAL SMALL CLAIMS COURT]. 

In that legal action, Claimant will seek judgment for the full principal sum plus:
1. Maximum allowable statutory pre-judgment and post-judgment interest;
2. All court filing fees and costs of service of process;
3. Reasonable attorney fees and collection costs where authorized by state statute (e.g., Tex. CPRC Ch. 38 / Cal. Civ. Code § 1717).

A public civil judgment may adversely affect your business credit rating (Dun & Bradstreet, Experian Business), and will be subject to bank levy, accounts receivable garnishment, and judgment liens against company assets.

I urge you to treat this matter with the utmost seriousness and satisfy this indebtedness promptly.

Sincerely,

__________________________________________________
[YOUR NAME / TITLE]
[YOUR BUSINESS / LLC NAME]
Claimant / Creditor