Invoice Disputes: What To Do When Your Customer Doesn't Agree
You send a correct invoice. A few days later you get an email back: "I don't agree with this." No payment, and now a problem on top.
It's more than an inconvenience. It feels like a block on money you've already earned. But a dispute isn't a verdict. It's a starting point. What you do in the first few days decides whether this becomes a quick formality or a drawn-out file that drags on for months.
What does it mean when a customer disputes your invoice?
An invoice dispute means your customer tells you, in writing or verbally, that they disagree with (part of) the invoice: the amount, the service delivered, or the terms. Once that happens, the invoice is no longer "undisputed". Its status changes, and that affects how you're allowed to collect it.
More than 40% of Belgian businesses deal with late payments. Some of that hides behind a dispute. Sometimes justified, often just a stalling tactic.
Formal objection or informal dispute: is there a difference?
In practice, people use these terms loosely. Legally, a formal, timely, written objection is the stricter standard, usually within a period set out in your terms and conditions. A dispute is broader: any form of disagreement, even a phone call or a stray email.
That distinction isn't theoretical. A late or unmotivated objection often doesn't count as valid. Your invoice then remains undisputed after all.
What do you do when a customer disputes the invoice? 4 steps
- Respond within 3 days. The 3-day check applies here too: the faster you respond, the smaller the chance the dispute grows into a matter of principle. Silence gets read by your customer as "no pushback."
- Ask for the dispute in writing. A verbal complaint is fleeting. Ask your customer to confirm their objection in writing. That forces them to get specific, and gives you a paper trail.
- Check the dispute against your own file. Does the delivery match, the quantity, the agreements? An invoice that's complete and correctly drawn up settles most disputes without discussion.
- Decide: justified, partly justified, or not justified. Each of the three calls for a different approach. Which is exactly the next point.
Is the dispute justified? A checklist
A justified dispute gets resolved with a credit note or an adjustment. Quickly and without friction, because that builds trust for the next invoice.
A partly justified dispute needs a middle ground: adjust the amount where needed, and reconfirm the rest in writing.
An unjustified dispute is where it gets sharp. This is where the Sergeant method applies: clear, consistent, no detours. "Sorry, I never got your email" is the excuse you'll hear most. It doesn't hold up if you're using registered mail or a read receipt.
When does a dispute become a stalling tactic?
Some customers don't dispute because they have a point, but because it buys time. Warning signs: the dispute only comes after a reminder, it's vague instead of specific, or the argument keeps shifting.
In that case, bringing in an external partner is already a signal on its own. Debtors give priority to the creditor who stays consistent. Mentioning an external party makes it immediately clear that stalling is no longer an option.
When should you bring in Bizzon?
Once a dispute costs you more of your own time than the amount is worth, it's no longer a side task. Bizzon takes over the follow-up: from the first response to escalation as leverage. So you don't have to put your customer relationship on the line yourself.
Target result: payment within 17 days of the invoice date, even if a dispute comes up along the way.
Frequently asked questions
Do I always need to get a dispute in writing?
Not required, but recommended. A written dispute gives you a paper trail and forces your customer into concrete arguments.
Can my customer just dispute an invoice to avoid paying?
Yes, it happens. A dispute doesn't automatically suspend payment if it isn't timely or well-motivated. Hence the importance of a quick, correct response.
What's the difference between a disputed and an undisputed invoice?
An undisputed invoice can be collected faster and with less discussion. Once a customer disputes it, the process changes, and an external partner is often faster than negotiating it yourself.
Payment Culture in Belgium: What the Numbers Really Say About Risk, Credit Checks and Cash Flow
Payment Culture in Belgium: What the Numbers Really Say About Risk, Credit Checks and Cash Flow
Invoices arriving late are no longer an unfortunate exception, but a structural feature of how companies in Belgium and the rest of Europe do business with each other. The annual report from the EU Payment Observatory, an initiative of the European Commission that monitors payment behaviour between companies and governments, shows that more than half of European businesses are affected by late payments.
In this respect, Belgium performs no worse than the European average, but certainly not fundamentally better either. And that is exactly where the problem lies: for an SME, "average" is no comfort when a single major defaulting customer can put your cash flow at risk.
For anyone dealing with invoicing, follow-up and customer relationships on a daily basis, the question isn't "does the problem exist", but "what do I do about it". This article runs through the key questions on payment behaviour, credit checks and cash flow in the Belgian B2B context.
How bad is the problem of late payments in Belgium, really?
Fairly bad, but not exceptional: Belgium sits around the European average, which means a significant share of businesses here are structurally paid late.
That "average" is misleadingly reassuring. The EU Payment Observatory finds that average payment terms in both B2B and government transactions exceed 60 days, and that the share of companies affected by late payments has, if anything, increased rather than decreased in recent years. For an SME with limited financial buffers, that isn't an abstract European figure but a concrete liquidity risk: every invoice that arrives 30 days late is 30 days during which you have to pre-finance suppliers, wages and taxes yourself.
Why does the government pay slower than businesses do among themselves?
The explanation often lies in internal procedures: verification periods, approval workflows and administrative checks delay actual payment, even when the statutory term (usually 30 days) is much shorter.
Belgium is no exception here. The European Commission has previously referred our country, along with several other member states, to the Court of Justice for incorrectly transposing the European directive against late payment. Even within the federal government itself the problem is acknowledged: the FPS Justice announced that from 2026 it will itself apply late-payment interest when it pays its own service providers late — an indirect confirmation that "government pays slowly" is not a myth but an established fact that even the legislator is now responding to.
What does slow payment actually cost your business in cash flow?
Every day an invoice remains unpaid is a day your business is missing working capital it needs elsewhere — for stock, staff, investments, or simply a buffer.
This translates directly into DSO (Days Sales Outstanding): the longer customers take to pay, the larger the amount that stays permanently "in transit" instead of in your account. Many SMEs offset this with a credit line or supplier credit, but that is not a free solution. It costs interest, limits your flexibility, and makes you more vulnerable when several customers pay late at the same time. Cash flow problems caused by late payment are therefore one of the most common causes of bankruptcy among otherwise healthy, profitable businesses.
What exactly is the link between credit checks and cash flow?
Credit checks and cash flow are directly linked: by checking a customer's creditworthiness before you accept or deliver an order, you avoid making your cash flow dependent on customers who structurally pay late, or not at all.
A credit check is not a bureaucratic formality but a preventive cash flow tool. Where reactive credit management only kicks in once an invoice is already overdue, a credit check intervenes before the risk materialises: you already know a customer's payment behaviour, financial health and risk profile at the start of the relationship. Businesses that invest in this typically see a direct correlation between fewer defaulting customers and a more stable, more predictable cash flow — precisely because they either avoid high-risk customers or approach them with adjusted terms (deposit, shorter payment term, bank guarantee).
How do you approach credit checks and cash flow in practice, in your own business?
Start with a standard credit check for every new customer, set clear payment terms, and ensure consistent follow-up from the very first day an invoice becomes overdue — not just after three reminder emails.
In practice, this means: running a creditworthiness check at onboarding (not only for large orders), setting payment terms explicitly and in writing, and automating a follow-up process so an overdue invoice doesn't sit unattended for weeks. For SMEs without their own credit management department, this is often exactly the step that gets skipped — not out of unwillingness, but for lack of time and specialised tools. That is also precisely where a structured approach, or external support, makes the difference between collecting after the fact and reducing risk beforehand.
Following up reactively or limiting risk proactively. Which do you choose?
The answer the figures suggest is clear: businesses that invest today in credit checks and structured follow-up build a real competitive advantage over businesses that only react once an invoice is already overdue.
Belgium's payment culture will not change overnight, and the government won't suddenly start paying faster either. What an SME does have control over is how it manages its own customer portfolio: who it extends credit to, under what conditions, and how quickly it acts when a payment doesn't come in. Credit checks and cash flow are therefore not separate topics, but two sides of the same coin - and that is exactly what makes preventive credit management more relevant today than ever.
Want to know what your own payment behaviour and risk profile actually look like? Feel free to get in touch, we're happy to think along with you about an approach that fits your business.
Sources: EU Payment Observatory (annual report, European Commission / CEPS / EY); European Commission, press release on referring Belgium to the Court of Justice over the late payment directive; FOD Justitie (Belgian Federal Public Service Justice), communication on the application of moratory interest; Creditsafe/Graydon, figures on Belgian bankruptcies.
Sending an effective payment reminder: how to get that invoice paid
By Gert Bellemans, managing director of Bizzon. Last legal review: October 2026.
A formal payment reminder is a written demand to pay an overdue invoice within a fixed period. You send it once a friendly reminder has had no effect. With a business customer (B2B) you may charge interest and compensation straight away. With a consumer (B2C) you must first send one free reminder and wait at least 14 calendar days.
In short:
- Work with a fixed four-step process, so you do not have to decide again for every invoice.
- Use a separate letter for B2B and for B2C; the legal rules differ considerably.
- Make sure you can prove that your reminder arrived. Without proof, your position is weak.
👉 Request the free payment reminder templates
How do you send a payment reminder? A 4-step plan
Decide in advance which step you take on which day. The biggest pitfall is that every unpaid invoice becomes a new, emotional decision: “Shall I give them one more chance?” That hesitation costs time and money.
- Friendly payment reminder (day 1 to 7 after the due date). Short and businesslike. State the outstanding amount, the invoice number and the payment details. No threatening language: the invoice may simply have been overlooked.
- First formal reminder (day 8 to 14). Refer to your earlier reminder, set a new final payment date (usually 14 days) and point out the consequences: statutory interest and a compensation clause.
- Second reminder or notice of default (day 15 to 30). The last step before handing over. State that you will pass the claim to a debt collection agency and that the additional costs are for the debtor.
- Handover to a debt collection agency (from day 30). Bizzon takes over the file from € 49 per file. Clients are paid within 17 days on average.
Already sent two reminders without result? Then this is the moment to hand over. 👉 Start your file from € 49
What is the difference between a B2B and a B2C payment reminder?
A consumer is far better protected by law than a business. In B2C you must first send a free reminder and the costs are capped; in B2B you may charge interest and costs from the first day after the due date.
| Business (B2B) | Consumer (B2C) | |
|---|---|---|
| Legal basis | Act of 2 August 2002 | Book XIX of the Belgian Code of Economic Law, since 1 September 2023 |
| Reminder mandatory? | No | Yes, one free reminder |
| Waiting period | None | 14 calendar days; by post it starts on the third working day after sending, by e-mail on the following day |
| Interest | 10.5% per year in 2026, from the due date | At most the reference interest rate + 8 percentage points, only after the waiting period |
| Compensation | Fixed sum of € 40 per invoice, plus whatever your terms provide | Up to € 150: max. € 20. From € 150.01 to € 500: € 30 + 10% of the part above € 150. Above € 500: € 65 + 5% of the part above € 500, capped at € 2,000 |
| Tone | Businesslike and direct | Clear, without legal jargon |
What must the free reminder to a consumer contain?
The first reminder must state the amount due, the compensation you will charge after the period expires, your name and company number, a description of the product or service supplied, and the payment period of 14 calendar days. You may not charge any costs for it, including file or administration fees.
What do you risk if a B2C reminder contains a mistake?
With a mistake you risk losing not only your right to costs and interest, but even your right to the principal amount. If the consumer files a complaint, the costs of the investigation are moreover borne by the party complained about. The burden of proof lies with you as the business.
That is why many business owners have their consumer files handled by a specialist. 👉 Let Bizzon handle your B2C files
Do you have to send a reminder first in B2B?
No. As soon as the payment term has expired, you may hand the claim straight to a debt collection agency. We still recommend one formal reminder: it is usually faster, cheaper and less damaging to the relationship than going straight to court.
What should a payment reminder contain?
A good payment reminder contains six elements and leaves no room for doubt:
- The outstanding amount, exact, in euro.
- The invoice number, with a copy of the invoice attached.
- A new final payment date. In a first formal reminder, 14 days after receipt is customary.
- The payment details: IBAN and the payment reference.
- The consequences of non-payment: statutory interest and the compensation clause.
- The next step: handover to a debt collection agency, with the additional costs for the debtor.
Rather not write it yourself? 👉 Request the ready-made templates
Do you have to send a payment reminder by registered post?
No, that is not a legal requirement. A reminder by ordinary post or by e-mail is in principle sufficient. For larger amounts or persistent non-payers, registered post is sensible, because it proves that the letter reached the debtor's address.
Our advice: send the reminder both by registered and by ordinary post. That way your customer can never claim in court that he received nothing. Keep all correspondence and proof of sending.
Is a payment reminder by e-mail valid?
Yes. Since 1 January 2023 the new Belgian Civil Code recognises notification by electronic means as a valid means of communication. But “I sent the e-mail” is not proof. You must be able to show that the recipient has seen your e-mail.
You have that proof in two cases:
- The customer has replied to your e-mail.
- You have received an electronic read receipt.
Without that proof, the burden of proof lies entirely with you. In practice, a lawyer will not start a case without it. No response to your e-mail? Then follow up by post or confirm by telephone.
Tip: request a read receipt for your own invoices, reminders and notices of default, and be careful about confirming read receipts on incoming e-mails yourself.
Tired of chasing payments? Hand it over
Bizzon takes over the follow-up of your unpaid invoices from € 49 per file. You supply the invoice and your earlier reminders; we handle the communication with your customer, diplomatically and decisively.
- Paid within 17 days on average
- 4.4 out of 5 on Google
- More than 10 years of experience in debt collection for Flemish SMEs
“After 3 months I still had an outstanding invoice, and even after 4 payment reminders nothing was moving. I then came across Bizzon, and thanks to your work the invoice was paid after 1.5 weeks! Great work, so in future I know exactly where to find you.”
Wannes de Jong, Google review (translated from Dutch)
👉 Start your file from € 49 or contact us on +32 11 46 90 00.
Frequently asked questions about payment reminders
How many payment reminders do you have to send?
For a consumer, one free reminder is legally required. For a business there is no mandatory number. In practice, a process of one friendly reminder and two formal reminders works best.
May you charge costs for a payment reminder?
For a business you may do so from the first day after the due date: interest plus a fixed sum of € 40. For a consumer the first reminder is free, and only after 14 calendar days may you charge the legally capped compensation and interest.
How long do you have to wait after a payment reminder?
For a consumer at least 14 calendar days after the free reminder. For a business you set the period yourself; 14 days is customary.
What is the difference between a friendly reminder, a formal reminder and a notice of default?
A friendly reminder is a polite request to pay. A formal reminder is a demand with a final date and the consequences. A notice of default is the last formal warning before a debt collection agency or the court.
When do you call in a debt collection agency?
As soon as your reminders remain without result, usually around day 30 after the due date. For a business it is allowed as soon as the payment term has expired. At Bizzon this is possible from € 49 per file.
What does a debt collection agency cost in Belgium?
At Bizzon you start from € 49 per file. In B2B files you can recover the statutory interest and the compensation clause from the debtor.