Recovering unpaid invoices starts with a structured follow-up process and escalates from there, moving through formal demand letters, collection agencies, and if necessary, legal action. Most unpaid invoices get resolved with persistent, professional communication before you ever need to involve a third party. The key is acting quickly and following a clear timeline.
Start With a Follow-Up Schedule
The longer an invoice goes unpaid, the harder it becomes to collect. A polite reminder sent a few days after the due date resolves more invoices than any other step in the process. Reference the original invoice number, the amount due, and the payment method, then ask if there’s anything holding up payment. Many late payments are the result of a lost email, a staffing change, or a simple oversight.
If that first nudge doesn’t work, follow this general escalation timeline:
- 7 to 10 days past due: Send a more direct email. Restate the overdue amount and offer to help resolve any issues, like a disputed line item or a missing W-9.
- 14 to 21 days past due: Send a firm, formal reminder. Attach a copy of the invoice and request full payment by a specific date.
- 30+ days past due: Send a final notice. State clearly that continued nonpayment may result in further action, such as involving a collection agency or pursuing legal remedies.
Every message should be in writing (email is fine) so you have a documented trail. Keep the tone professional even when you’re frustrated. Angry messages rarely speed up payment and can complicate things if the dispute ends up in court.
Send a Formal Demand Letter
If your final notice gets ignored, a formal demand letter is the next step. This is a written letter, often sent by certified mail, that lays out the amount owed, the original payment terms, the history of your attempts to collect, and a firm deadline (typically 10 to 15 days) for payment. It should also state what you plan to do if payment isn’t received, whether that’s hiring a collection agency, filing in small claims court, or both.
A demand letter serves two purposes. First, it often prompts payment because the client realizes you’re serious. Second, it creates a legal record showing you made a good-faith effort to resolve the matter before escalating. Some courts expect to see evidence of a demand letter before they’ll hear your case. You can write the letter yourself or have an attorney draft one on letterhead, which tends to carry more weight.
Charge Late Fees and Interest
If your original contract or invoice includes a late fee clause, now is the time to apply it. Common structures include a flat fee (like $25 or $50 per month) or a percentage of the outstanding balance (often 1% to 1.5% per month). Include the updated total in your demand letter and every subsequent communication.
If you didn’t include late payment terms in your contract, you may still be able to charge interest. Many states set a statutory interest rate that applies to overdue debts even without a written agreement. The federal prompt payment rate, which applies to government contracts and serves as a benchmark, is 4.125% per year for the first half of 2026. State rates vary and can be higher. Check your state’s statute to confirm what you’re allowed to charge.
The practical value of late fees goes beyond the extra dollars. They create financial pressure that motivates clients to prioritize your invoice over other bills.
Hire a Collection Agency
When your own collection efforts have failed, typically after 60 to 90 days of nonpayment, a collection agency can take over. Most agencies work on a contingency basis, meaning they take a percentage of whatever they recover and you pay nothing upfront. Contingency fees for commercial debt typically range from 15% to 50% of the recovered amount. The rate depends mostly on how old the debt is: invoices that are 60 to 90 days overdue usually fall between 15% and 25%, while debts over six months old can cost 30% to 50% to collect.
Some agencies also offer flat-fee models, charging $10 to $50 per account regardless of outcome. This structure works better for high-volume, low-dollar situations where you have many small invoices to chase. For a single large unpaid invoice, contingency is usually the better fit because you only pay when money comes in.
Before hiring an agency, verify that they’re licensed in the states where your clients are located, and ask how they communicate with debtors. An overly aggressive agency can damage your business relationships and create legal liability for you.
File in Small Claims Court
Small claims court is designed for disputes involving relatively modest amounts, and you typically don’t need a lawyer. Claim limits vary widely by state, ranging from $2,500 on the low end to $25,000 on the high end, with most states capping claims somewhere between $5,000 and $10,000. Filing fees are generally under $100 for smaller claims.
To file, you’ll go to the small claims court in the county where the client is located (or where the work was performed, depending on your state’s rules). You’ll fill out a claim form, pay the filing fee, and the court will schedule a hearing, usually within 30 to 60 days. Bring your contract or written agreement, the invoice, all email correspondence, proof of the work you delivered, and your demand letter.
If the judge rules in your favor, you’ll receive a judgment for the amount owed. That said, a judgment doesn’t automatically put money in your account. If the client still refuses to pay, you may need to pursue enforcement options like wage garnishment or a bank levy, which vary by state.
Consider Larger Legal Action
If your unpaid invoice exceeds your state’s small claims limit, you’ll need to file in a higher civil court. This process is more formal, typically requires an attorney, and takes longer to resolve. Attorney fees and court costs can add up, so weigh the amount you’re owed against the cost of litigation before proceeding.
One middle-ground option is sending an attorney’s letter before filing suit. The cost is relatively modest (often a few hundred dollars), and many clients pay up once they see a law firm’s letterhead. If litigation does become necessary, some contracts include a clause requiring the losing party to cover attorney fees. If your contract has that language, it significantly reduces your financial risk in pursuing the case.
Prevent Unpaid Invoices in the Future
The best collection strategy is one you never have to use. A few contract and billing practices dramatically reduce the odds of chasing payments later.
Require a deposit or milestone payments for large projects. Collecting 25% to 50% upfront means you’re never fully exposed if a client stops paying. For ongoing work, bill on shorter cycles (biweekly or monthly) rather than letting a large balance accumulate over several months.
Put your payment terms in writing before any work begins. Your contract should specify the payment due date (net 15 or net 30 are common), the late fee structure, and what happens in the event of a dispute. Even a simple email agreement is better than a verbal understanding, though a signed contract is stronger in court.
Run a basic credit check or ask for references before taking on a new client with a large project scope. If a potential client has a pattern of late payments, you’ll want to adjust your terms accordingly, perhaps requiring full payment upfront or shorter billing intervals. When clients know from the start that you have clear terms and enforce them, they’re far more likely to pay on time.