An unpaid invoice needs a diagnosis before it needs a stronger message. A client who never received the invoice, a client waiting on approval, a client disputing the amount and a client who has simply gone quiet each need a different next step. This guide gives you a decision table, then points you to the page that covers each situation in detail.
What is an unpaid invoice? Start with the facts
Before you contact the client, collect five things from your own records:
- The invoice number, amount, currency and issue date.
- The due date and the payment terms you both agreed.
- Where and when you sent the invoice, and to whom.
- Every reply you have received, with dates.
- Any payments you have verified in your own bank or payment account.
A payment someone says they made is a claim, not a received payment. Only reduce the balance after you have seen the money yourself.
A fictional example used on this page
The fictional invoice INV-104 is Alex’s USD 1,200 design invoice for Jordan, issued March 2, 2026. Alex and Jordan agreed on Net 30, counted from March 2. Counting 30 calendar days gives a due date of April 1, 2026. On April 4 and April 8, Alex plans two follow-ups. Those dates are only an illustration, not proven best timing. All amounts are in USD.
Decision table: what is going on, and what to do next
| Situation | What you may see | Check first | Next action |
|---|---|---|---|
| Invoice may be missing | No reply, no open, wrong or old address | Was it sent to the right billing contact? | Resend with the invoice attached, ask for a quick confirmation of receipt |
| Stuck in approval | "It's with accounts" or "waiting on sign-off" | Who approves, and what do they need? | Ask for the approver's name, the expected step and whether a PO number is missing |
| Wrong amount | Client says the total looks off | Compare invoice against quote or contract | Confirm what is right, correct the document if you made an error, and ask for payment of the undisputed part if that is agreed |
| Dispute about the work | Complaint about quality or scope | What did you agree in writing? | Stop routine reminders, reply to the substance, propose a resolution |
| Client says it is paid | "I sent it last week" | Is the money visible in your account? | Ask for the date, amount and a transfer reference. Keep the full balance until you verify |
| Partial payment | Part of the amount arrives | What did the client say it covers? | Record the verified amount, state the remaining balance, restate the date for the rest |
| No reply | Silence after several messages | Did you reach the right person? | Try another contact or channel, then decide whether to escalate |
Missing or misdirected invoice
Start here when you have no sign the client has seen the invoice. Resend it to the person who pays bills, and ask a simple question: "Can you confirm you have it?" Check receipt and the agreed start date before asserting that payment is late.
If you want wording for the early reminder stage, see email examples for invoice follow-up.
Waiting on approval
An approval delay can look like silence. Ask who signs off and what they need: a purchase order number, a project code, a different billing address. Then put the answer in writing and set your next check-in date. A specific question helps identify the next step, especially if your contact does not control payment.
Wrong amount or disputed invoice
When the client questions the figure or the work, pause routine reminders. A standard reminder does not answer the question raised in a dispute.
Go back to what was agreed: the quote, the contract, any change requests. If the invoice contains your mistake, issue a corrected document in your invoicing tool and say so plainly. If you believe it is right, explain the line items. If only part is disputed, ask whether the undisputed part can be paid while you resolve the rest. Whether you may charge for the full amount depends on your agreement, so check the contract wording rather than assuming.
"I already paid"
Treat the statement as information to check, not as settlement. Reply with something like:
MoneyNudge shows which quotes and invoices need a follow-up today. It drafts each follow-up from your own template; you review it and send it from your own email. It never emails your clients on its own. It keeps a record of what you marked as sent, and when.Thanks, Jordan. Could you send the payment date, amount and any transfer reference? I'll check on my side and confirm.
If the payment turns out to be partial, record the verified amount only. A verified USD 400 leaves USD 800. If nothing has arrived, tell the client what you found, using facts, not accusations.
If the reference points to a different invoice, match it carefully before reducing either balance. Ask the client to clarify which document the payment covers rather than guessing.
Partial payment
Say what arrived and what remains, in the same currency. Example for INV-104: "Thanks for the USD 400 payment, which I've received. The remaining balance is USD 800. Can you confirm when I can expect it?" Keep wording separate from the original invoice amount so the client can match the numbers. For wording across overdue stages and partial balances, see overdue invoice email templates.
When a client not paying invoices needs a different response
Check whether this is a contact problem or a genuine refusal before taking another step. An absent reply is not evidence that the client accepted your invoice, read your message or intends to avoid payment. If the billing contact has changed, correct that first. If they identify an approval delay, ask what document or person is missing and agree the next check-in. A disputed deliverable requires a response about the work rather than another request for a date.
Keep these reasons separate in your record. “Waiting for approval” and “payment claimed” are not interchangeable, because one asks for an administrative next step and the other asks you to verify money. If the client asks to wait, write down the actual agreed date. Check other open issues before resuming a reminder so one resolved issue does not hide another.
How to collect unpaid invoices: a verification checklist
For a claimed payment, write down what the client actually says was sent, including currency, amount, date and reference. Check the matching account or payment service yourself. A screenshot or transfer reference can help locate a payment, but neither replaces your own confirmation. Do not record the full original invoice as paid simply because part of it appears.
Once you confirm the payment, record the received amount and date and calculate what remains in the same currency. For the fictional USD 1,200 invoice here, a verified USD 400 payment leaves USD 800. If you cannot find the claimed payment, tell the client exactly what you checked and ask for the missing reference or recipient details. Avoid assuming dishonesty or sending the earlier overdue message unchanged.
When a payment plan is agreed, record each amount and date in writing, plus what happens if a date is missed. Ask the client to confirm the arrangement. Keep that plan alongside the original invoice and record only actual payments as received. Check whether the plan changes terms or fees before treating it as a settled agreement.
No reply
Silence after a few messages calls for a change of approach, not louder language. Try a different contact, a short phone call, or a note on a different channel. Keep a record of each attempt with its date.
If you still hear nothing, your options depend on your agreement, the amount and your location. They may include a formal letter, a payment plan, a collection service, a small claims filing or writing the amount off. Whether any of these is available or worthwhile varies, and some carry costs or rules. Before you take a formal step, check your contract and your local court or government guidance, or ask a qualified adviser.
Before a formal collection or legal step
A routine reminder is different from a formal demand-letter guide. Keep the contract, invoice, delivery evidence and correspondence together before deciding whether a formal letter is appropriate. Do not add a fee or threaten a step merely to make the message sound stronger.
The Federal Trade Commission's debt-collection guidance describes protections for covered consumer debts; business debts may be treated differently. Do not assume a rule for consumer collection applies to your client invoice or gives you permission to contact someone repeatedly. Check the scope and local rules for the situation.
Court procedures, eligibility and limits depend on location. The California Courts small-claims guide is an official starting point for California, not a rule for every state or country. Compare the evidence, filing costs and time involved, and ask a qualified adviser when jurisdiction or the claim is unclear. Winning a case and recovering money are separate outcomes.
If you consider writing an amount off, the IRS bad-debt guidance explains US tax distinctions. An unpaid invoice does not automatically create a deductible loss; accounting method and other facts matter. Take those facts to your accountant rather than treating a write-off as a universal final step.
For earlier stages, return to the past due invoice plan.
Keeping the process organised
Keep the invoice reference, agreed terms, last contact and next decision together. Note what you checked and where the evidence lives. Update the record after each reply or verified payment, so your next message uses the current balance and addresses the actual obstacle.
Frequently asked questions
What counts as an unpaid invoice?
An unpaid invoice has not been paid in full. It becomes overdue after the agreed due date passes, subject to your agreement and applicable rules. Start by checking the invoice, recipient, amount and payment records. Receipt problems, approval delays, a dispute and silence need different responses, so diagnose the reason before escalating.
Should I send a reminder if the client disputes the invoice?
Answer the dispute first rather than treating it as another missed deadline. Compare the invoice with the agreed work and any change requests, then respond to the specific concern. If you made an error, correct it. An undisputed part may be handled separately if agreed, but avoid implying every dispute removes all payment obligations.
Does a client saying they paid reduce the balance?
A message saying payment was sent is a claim to check, not confirmation that money arrived. Pause routine reminders and ask for the date, amount and reference. Check your own bank or payment account. Keep the existing balance until verification; subtract only a confirmed payment in the same currency, not the amount merely claimed.
When should I consider a lawyer or court?
The choice depends on the amount, evidence, agreement and jurisdiction. Gather the contract, invoice, records of work and correspondence first. Read official court guidance for the relevant place and weigh cost and time. A qualified adviser can help with uncertain eligibility or jurisdiction. Do not assume a judgment guarantees recovery.
Can I charge interest on an unpaid invoice?
Check your agreement and the law that applies to the invoice before adding interest or a late fee. Some places provide statutory rights in defined circumstances, while others impose limits or require agreed terms. Do not copy a rate from a generic template. Link the client to the actual relevant clause or obtain qualified advice.