Free US Late Fee Calculator and Demand Letters for Invoices
Enter your overdue invoices and get a friendly reminder, a second notice or a final demand letter, ready to print or email with your own logo and payment details. Keep it simple and just ask for what you are owed, or add the late fees and interest from your contract and have them worked out to the cent.
Late fees come from what you agreed. In the US there is no single national rule that adds interest to a late business invoice, and state rules differ, so this tool works from your own contract or invoice terms. What to check for your state
How do you want to chase this?
Late fees and interest are optional, and in the US they depend on what you agreed and on your state. Plenty of people simply want to be paid and would rather not add anything on top. Both ways are fine. Pick the one that suits you. You can switch at any time.
Your invoices, letters and details are saved in this browser only, so you can come back later.
Add your overdue invoices
Invoices you have already sent that are past due: still unpaid or part paid.
Names and addresses (optional)
Your details and your customer’s appear on the letters. Kept in this browser only, never uploaded.
What the figures come to
The unpaid amount on your overdue invoices. It updates as you type.
Your result appears here as soon as you have entered an invoice amount and a date.
Your letters
Three letters, from gentle to firm. Pick the one that fits where you are with this customer. Each one simply asks for the unpaid amount.
Add an overdue invoice in step 1 and your letters appear here.
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What you get
Three letters you can make, built in your browser. Click one to see the example in full.
Made-up business, customer and invoices.
Chasing a late payment is awkward, and getting the figures wrong makes it worse. This tool does the arithmetic and writes the letter, so you can concentrate on getting paid.
What to check for your state
Interest and late fees are controlled by state law, and the rules differ a lot from one state to the next, sometimes as much as between countries. This tool does not know your state’s rules and does not decide what you may charge. Before you send a demand, check:
- Your contract or invoice. Is the late fee or interest written down and agreed? Does the contract name a state’s law (a “governing law” clause)?
- Your state’s rules on interest and late fees. Some states limit them, and the rules can differ for businesses and for private individuals.
- Court limits. The small claims limit and the time limit for suing, in the place a claim would be brought.
- Different states. If you and your customer are in different states, the rules can differ. Which state’s law applies depends on your contract and the facts.
A good starting point is the list of official state government websites.
What you can adjust
- A grace period, so nothing is charged for the first few days.
- A flat late fee and a one-time percentage fee, each charged once.
- A recurring rate per day, week, month or year, charged day by day, in full for each period that starts, or only for complete periods, whichever your contract says.
- A cap on the total, as a dollar amount or a percentage of the invoice.
- Part payments and invoices that were paid late.
- Three letters from gentle to firm, written as “I” or “we”, with your logo, address and payment details.
How the figures are worked out
Interest is simple interest: the unpaid balance times the rate times the days, divided by a 365-day year, rounded to the nearest cent. A rate quoted per month is multiplied by twelve to get its yearly equivalent, so 1.5% a month is 18% a year. A payment made on a given day does not reduce that day’s charge. When a part payment changes the balance, the period is split at that point. Fixed fees are charged once, and if your terms include a cap, the lower cap applies.
Important
This tool gives general information only. It is not legal, financial or tax advice, and using it does not create an attorney-client relationship. Laws, interest rates and court limits change and may not be current. The letters are templates built from the details you type in. Read them, check every fact, and check your contract and the official sources before you send anything. If you are unsure, or the amount is large, speak to a licensed attorney in your state.
Common mistakes
- Sending a final demand before a friendly reminder. Start gently, then get firmer.
- Charging a late fee that was never in your agreement.
- Leaving out the amount, the invoice number or the date it was due.
- Treating the letter as legal advice. Rules differ by state, so check yours before you claim anything.
Questions
Do I have to charge a late fee or interest?
No. Late fees and interest are optional, and many people just want to be paid and would rather not add anything on top. Choose "Just ask for what I’m owed" at the top of the tool and the letters ask for the unpaid invoice amount only, with no calculation.
Can I charge a late fee if my contract does not mention one?
Generally a late fee has to have been agreed in advance, for example in a signed contract or in invoice terms your customer accepted. Without agreed terms there is usually no late fee to add, but some states allow interest at a legal rate. Check your contract and your state’s rules.
What does "1.5% per month" work out to?
It is a simple yearly rate of 18%: 1.5% times twelve months. On a $5,000 invoice that is $75 for a full month, or about $2.47 for each day it is overdue.
What is a grace period?
A set number of days after the due date during which no late fee or interest is charged. If the invoice is paid within the grace period, nothing is added.
What should I send first, a reminder or a demand letter?
Most people start with a friendly reminder, then send a firmer second notice, and use a final demand only when earlier requests have not worked. The tool suggests one based on how overdue your oldest invoice is, but the choice is yours.
Is the information on the page legal advice?
No. It is general information only, not advice. Laws differ by state and change, and your own contract matters most, so check your own terms and your state’s rules before you send anything. If you are unsure, speak to a licensed attorney.
Are my invoice details uploaded anywhere?
No. The calculation and the PDFs are made in your browser. Your details are only kept in your browser so you do not have to type them again, and you can clear them at any time.
Based in the UK? Use the UK Late Payment Calculator instead. For a simple flat-rate sum, try the Invoice Late Fee Calculator.