5 Lines to Add to Your Payment Terms Before the Next Unpaid Invoice
Disclaimer: Key Debt Recovery is a collection agency, not a law firm, and nothing in this post is legal advice. Rules on late fees, interest, personal guarantees and contract terms vary by state and by industry. Have an attorney licensed in your state review your payment terms before you use them.
Most unpaid invoices are decided before the work even starts. When a customer stops paying, the first question any collector, attorney or judge asks is simple: what did they agree to? If the answer is a handshake and an invoice that says "Net 30," your options shrink fast.
The problem is growing. Nearly 3 in 5 small businesses (59%) now have invoices overdue by more than 30 days, up from 47% a year earlier, and the average business with unpaid invoices is owed $17,700, according to the QuickBooks 2026 Small Business Late Payments Report.
Clear terms will not make every customer pay on time. They do make it much easier to get paid when one doesn't. Here are five lines worth adding before the next account goes quiet.
1. A Due Date That Leaves No Room for Interpretation
"Net 30" sounds clear until a customer argues the clock started when they received the goods, approved the work or got around to opening the invoice. Spell out when payment is due, when the clock starts and how you accept payment.
Shorter terms also help. In the same QuickBooks report, 55% of businesses on net-30 terms had overdue invoices, compared with 26% of businesses that require immediate payment.
Example: "Payment is due in full within 30 days of the invoice date. We accept ACH, check and card."
2. A Late Fee or Interest Rate, Agreed Up Front
A late fee that first appears on a past-due invoice is easy for a customer to dispute. A late fee they agreed to in writing before the first order is much harder to argue with.
Keep the rate reasonable. Every state sets its own limits on how much interest can be charged, and some treat business accounts differently from consumer accounts.
Example: "Balances not paid by the due date accrue interest at [X]% per month, or the highest rate allowed by law, whichever is lower."
3. Who Pays the Cost of Collecting
In the U.S., each side in a lawsuit generally pays its own legal costs unless a contract or statute says otherwise. This is known as the American rule. Without a clause that shifts those costs, the fees to recover a $9,000 invoice come out of the $9,000.
Example: "Customer agrees to pay all reasonable costs of collection, including collection agency fees, attorney fees and court costs."
Some states limit what can be recovered, so this is one line to have your attorney word carefully.
4. A Personal Guarantee From the Owner
Many customers operate as an LLC or a corporation, which protects the owner's personal assets. If the company closes or is drained of cash, a judgment against it can be worth very little.
A personal guarantee gives you a second person to collect from. It should be in writing and signed by the owner as an individual, not only as "President" or "Managing Member" of the company.
Example: "I, [name], personally guarantee payment of all amounts owed by [company] under these terms."
5. Where Disputes Get Decided
If your customer is two states away, chasing them in their home county adds travel, local counsel and delay. A governing law and venue clause settles that in advance. Courts generally enforce these forum selection clauses between businesses, unless enforcing them would be unreasonable.
Example: "These terms are governed by the laws of [state]. Any dispute will be decided in the state or federal courts located in [county], [state]."
Quick check-up
How many of the 5 lines are in your terms?
Tap each line you already have. Copy the ones you're missing and take them to your attorney.
"Payment is due in full within 30 days of the invoice date. We accept ACH, check and card."
"Balances not paid by the due date accrue interest at [X]% per month, or the highest rate allowed by law, whichever is lower."
"Customer agrees to pay all reasonable costs of collection, including collection agency fees, attorney fees and court costs."
"I, [name], personally guarantee payment of all amounts owed by [company] under these terms."
"These terms are governed by the laws of [state]. Any dispute will be decided in the state or federal courts located in [county], [state]."
Start with the due date. Every other line leans on it.
Sample wording only, not legal advice. Rules vary by state, so have your attorney adapt it.
Put the Terms Where They Count
Fine print on the back of an invoice is better than nothing, but it may not hold up on its own. For sales of goods between businesses, the Uniform Commercial Code says added terms can become part of the deal, but not if they materially change it or the customer objects. Late fees and collection costs are exactly the kind of terms a customer will argue were never agreed to.
The stronger approach is a signed credit application or service agreement before the first order, with the same terms repeated on quotes and invoices. For existing customers, send the updated terms and ask for a signature before the next order ships.
If an Invoice Still Goes Past 90 Days
Good terms don't guarantee payment. They make recovery faster, cheaper and easier to prove. If an account has already stopped responding, the sooner it is reviewed, the better the odds.
Key Debt Recovery helps businesses recover past-due commercial accounts. If you are deciding whether to keep chasing it yourself, our guide to in-house collections vs. a collection agency walks through the trade-offs. When you're ready, submit an account or contact us to talk it through.