Key Takeaways

• A customer going quiet on a big invoice is a signal, and the right move changes by the week.
• Days 1 to 30 are for friendly reminders. Days 31 to 60 are for the phone. Days 60 to 90 is when a formal demand letter belongs.
• Once an invoice passes 90 days, your chances of recovering it drop by more than half, and they keep falling.
• Past 90 days, a contingency collection agency almost always beats suing. It’s faster, it’s cheaper, and it costs nothing if it fails.
• The Fair Debt Collection Practices Act doesn’t cover business-to-business debt, which gives a commercial agency more room to work your account.
• Most silent customers aren’t trying to cheat you. They’re stuck, embarrassed, or disorganized, and the right approach brings them back to the table.

You did the work. You sent the invoices. You followed up politely with multiple clients more than once. And now there’s nothing. No reply, no callback, no explanation. Just a $15,000 accounts receivable hole where your money should be.

Here’s the frustrating part: most businesses have no plan for this moment. They send more emails, wait a few weeks, send some more, and six months later they’re writing all or part of the outstanding debt off. What they needed was a timeline, a willingness to actually follow it, and a commercial collection agency in their corner for accounts that won’t budge.

So here’s ours. Week by week, from the day an invoice goes late to the day that account belongs with a professional. One thing to keep in mind throughout: the customer who owes you usually isn’t a villain. Understanding that is what lets you get paid without torching a relationship you spent years building.

Why Customers Go Quiet (It’s Rarely What You Think)

Silence feels personal. It rarely is. A customer who stops answering is usually in one of four situations, and each one calls for a different tone from you.

• A cash crunch. They intend to pay and can’t right now, so they avoid the conversation instead of admitting it. This is the most common one by a mile.
• An unspoken dispute. Something about the scope, the quality, or a line on the invoice bothered them, and nobody ever raised it. It festers.
• Internal chaos. Your invoice is sitting with someone who left the company, or stuck in an approval queue nobody owns. No malice, just inefficient processes.
• Deliberate stalling. They’ve decided yours is one of the last invoices they’ll pay. This is the rarest of the four, and the one many people assume first.

Your job in the first 60 days is simple: make paying easier than avoiding you, and figure out which of those four you’re actually dealing with. Our guide to common unpaid debt excuses can help you tell them apart.

Days 1 to 30: Assume Good Faith

The first month is for reminders that let your customer fix an oversight without feeling cornered. Two or three contacts is plenty. Each one should restate the invoice number, the amount, the due date, and exactly how to pay.

Send the first reminder the day after the due date, and attach the invoice again. You’d be amazed how many late payments trace back to an invoice that never reached the right inbox.

Around day 10, send a statement of account and ask a direct question: is anything holding up payment? That one question surfaces disputes while they’re still cheap to fix.

Around day 25, send a firmer note that names the next step, which is a phone call.

Keep every message factual and every message in writing. Our guide to collection letters covers the wording. And log every contact with a date, because the paper trail you build now becomes the case file later.

Days 31 to 60: Pick Up the Phone

Email has generally maxed out its effectiveness by day 30. Month two is when you should start calling. But the goal is information, not confrontation.

Call accounts payable first. If you get nowhere, call whoever signed the order. Ask three things:

• Did the invoice arrive and get approved
• Is anything in dispute
• When is payment scheduled?

If the honest answer is “we can’t pay it all right now,” offer a payment plan on the spot. A customer who can commit to $500 a month will often clear a $5,000 balance that a demand for the full amount would push into permanent silence.

Two other moves should happen in this window. Put the customer’s credit on hold so nothing new ships until the balance is resolved. And if your contract allows late fees or interest, apply them now and advise the client you’re doing so. An accruing balance changes their priorities.

Get every promise in writing. Even a one-line email confirming the date they committed to.

Days past due	What to do	What you’re after
1 to 30	Two or three written reminders with the invoice attached. Ask directly if anything’s holding up payment.	Rule out a lost invoice or a silent dispute while it’s still easy.
31 to 60	Call accounts payable, then the decision-maker. Offer a payment plan, place a credit hold, apply late fees.	Turn silence into a commitment you can hold them to.
61 to 90	Formal demand letter, certified mail, 10-day deadline, stated next step.	One last unmistakable chance before a third party gets involved.
91 to 120+	Place with a collection agency, or negotiate a written settlement. If all options have failed, sue if the balance and time lapse justify the expense.	Recover the money while the odds are still on your side.

Days 61 to 90: The Demand Letter

It’s been two months of reminders and calls that haven’t produced anything. Now the account needs a formal demand letter, and this lets your customer know the informal phase is over.

A demand letter states the amount owed, the invoices it covers, a firm deadline (10 business days is standard), and exactly what happens when that deadline passes. Send it by certified mail, and email it the same day to cover your bases.

Keep the tone professional. A letter that reads as confrontational or angry can make the receiver defensive, create conflict, and possibly lose you that customer.

The 90-day mark matters for a reason beyond etiquette. Once an invoice passes 90 days past due, your chances of recovering it drop by more than half, and by even more after six months. A demand letter sent on day 60 gives you room to act before your odds of recovery fall off a cliff.

Days 91 to 120 and Beyond: Three Ways to Get Paid

After your deadline has passed without progress, there are three popular options, and they differ in cost, speed, and how much of your own resources they consume.

Option	What it costs	How long	When it makes sense
Professional collection agency (working on contingency)	A percentage of what’s collected. Nothing if they don’t recover anything.	Their goal is to get clients paid within 90 days of placement.	Most balances, and every case where you’d like to keep the customer.
A negotiated settlement	Whatever discount you agree to, if you accept less than the full balance.	As soon as the customer pays, or on a written payment schedule.	A customer who wants to pay but can’t cover it all, when some money now beats a long, drawn-out process.
A lawsuit	Attorney fees and court costs, unless your contract shifts them to the losing side. Small claims trims the costs, but it’s still a lawsuit.	Months in small claims. Several months to a few years for anything bigger.	Large balances, airtight contracts, a customer who’s ignored everything. Small claims only fits balances under your state’s limit.

A collection agency brings tools you simply don’t have. If your customer has moved or gone dark, a skip tracing department like ours that’s run by a licensed private investigator will actually find them. Businesses have credit files too, and credit bureau reporting gives a stalling client a very concrete reason to resolve things. If the account genuinely needs legal action, a collection agency like ours that offers full-service litigation services handles it, with every cost approved by you in writing first.

A negotiated settlement is the option people forget they have. If your customer genuinely can’t cover the full balance, a lump sum for less, or a firm payment schedule, can beat months of chasing. Get it in writing: a short acknowledgment of debt where the customer confirms the balance, that nothing’s in dispute, and the payment terms. If they miss a payment, that document strengthens your case from there.

Speaking of the law, the Fair Debt Collection Practices Act covers debts a consumer owes primarily for personal, family, or household purposes. It generally does not cover business-to-business debts, leaving a commercial collection agency more room to pursue your account quickly. State rules and basic human decency still apply, however, and the agency you pick should honor both.

How to Collect and Keep the Customer

A large outstanding balance probably belongs to someone who was a valuable client for you for years. How you collect decides whether they’re still a customer next year. The trick is separating the person from the balance. The invoice is a fact to be resolved. The relationship is something you can protect while resolving it.

That’s the whole idea behind our P.H.D. Philosophy (Preserve Human Dignity). No robocalls. No threats. No 9pm phone calls. Our collectors are seasoned pros who call to solve a problem and offer arrangements people can actually keep.

Is that being soft? Not even slightly. Our recovery rates run nearly double the industry average, and we’ve recovered more than $250 million for clients over 30 years. Respect isn’t the opposite of getting paid. We’ve proven it’s the most effective way to get paid. Our article on why professional collections protect business relationships goes deeper into why that works.

Nipping Past-Due Accounts in the Bud

Three habits at account opening can help mitigate these situations:

• Run a credit check and set a limit. Every account you open on terms is a small loan you’ve chosen to make. A limit keeps their financial issues from becoming yours.
• Put collection costs and late fees in the contract. A clause covering collection costs and interest is a reliable way to push recovery expenses onto a customer who caused them.
• Watch for the tells. A customer who pays later each month, disputes small items, or keeps changing your contact is raising red flags. Our post on warning signs of commercial debt lists the patterns worth acting on early.

Recover Your Debt & Peace of Mind

If a customer has ignored your reminders, your calls, and your demand letter, that account is likely best handled by a professional. We work commercial accounts nationwide on contingency, with no minimums, no quotas, and no fee unless we recover your money.

Did you find this article helpful? Just imagine how helpful our experts could be when it comes to your bottom line! Reach out to us for a free consultation. Tell us what’s owed and what you’ve already tried, and we’ll give you an honest read on what’s recoverable and how soon.

Frequently Asked Questions About Collecting an Unpaid Invoice

How long should I wait before sending an unpaid invoice to collections?

Most businesses should place a commercial account at 60 to 90 days past due, once the customer has ignored at least two written reminders, a phone call, and a formal demand letter. Once an invoice passes 90 days, the chance of recovering it drops by more than half, so waiting longer mostly reduces what comes back.

What should I do if a customer ignores my demand letter?

Treat the missed deadline as their answer and escalate that same week rather than sending another letter. For most balances, that means placing the account with a collection agency working on contingency, which costs nothing unless it recovers money and puts trained collectors on the file right away. Keep the demand letter, the certified mail receipt, and your contact log together, because they expedite recovery through an agency and would be vital if an account has to go through the legal process.

Can I charge interest or late fees on an overdue business invoice?

You can if your contract, credit application, or invoice terms say so, and many states also allow a statutory interest rate on overdue commercial accounts. Fees invented after the fact, with nothing in writing behind them, are hard to enforce and easy to dispute. Add a late fee and a collection-costs clause to your terms before you extend credit, then apply them consistently and mention them in your reminders and your demand letter.

How do I get paid on an invoice that’s 120 days late without suing?

Place it with a commercial collection agency working on contingency, and do it now. By 120 days, your reminders, calls, and demand letter have done what they can, and every extra month tends to shrink what comes back. An agency brings skip tracing, credit bureau reporting, and experienced collectors to the file, at no cost unless it recovers money. If the customer wants to pay but can’t cover the full balance, a written settlement for less, or a firm payment schedule, is another way to get paid without going to court.

Does the Fair Debt Collection Practices Act apply to business-to-business debt?

Generally, no. The FDCPA covers debts a consumer owes primarily for personal, family, or household purposes, so one company collecting an unpaid invoice from another usually falls outside it. But outside the FDCPA doesn’t mean anything goes. Some states require commercial collection agencies to be licensed or bonded, and some state laws reach further than the federal one. California, for example, extended its Rosenthal Act to certain business loans and financing owed by individuals, including debts someone personally guaranteed, starting July 1, 2025. Federal rules against deceptive practices, and on autodialed calls and texts to cell phones, apply no matter who owes the money. A reputable agency follows all of these and treats the people on the other end with respect while it’s at it.