Invoicing7 August 20264 min read

Creating an invoice: the legal requirements in the Netherlands

An invoice looks like a simple piece of paper, but the Belastingdienst sets strict requirements for it. If a mandatory element is missing, this can affect your VAT deduction and your client's. This article covers exactly which details are required, the mistakes entrepreneurs make most often, and what to do if an invoice turns out to be wrong.

Which details are required by law on an invoice?

The Belastingdienst sets out a fixed list of elements that must appear on every business invoice. Think of your full company name and address, your client's address, a sequential invoice number, the invoice date, and the date on which you delivered the service or product.

In addition, your VAT (btw) identification number is mandatory (the number under which the Belastingdienst knows your business for turnover tax purposes), and, if you are registered, your KvK number (your registration number with the Kamer van Koophandel, the Dutch Chamber of Commerce). A clear description of what you delivered also belongs on the invoice, with the quantity and unit price.

Finally, you must state the VAT amount separately from the amount excluding VAT, and which rate you apply: 21%, 9% or 0%. If you work under the small businesses scheme (a VAT exemption for low annual revenue, referred to below as the KOR), you state this explicitly instead of a VAT amount.

What is a sequential invoice number and why does it matter so much?

A sequential invoice number means that each number appears only once and that there are no gaps in the sequence that you cannot explain. The Belastingdienst uses this sequence to check whether you have declared all your revenue.

Many entrepreneurs choose a structure that includes the year, such as 2026-001, 2026-002, and so on. That keeps things organised, and each calendar year starts again from a logical point.

Avoid keeping track of numbers manually in a Word document or Excel file. A missed or duplicate number stands out quickly during an audit and can raise questions you would rather avoid. A bookkeeping system that automatically continues the sequence, such as TelMaar, largely removes this risk.

What mistakes do entrepreneurs make most often?

The most common mistake is a missing or incorrect VAT number, especially for new clients whose details have not yet been fully entered. Always check the KvK and VAT details before sending the first invoice.

A second frequent mistake is mixing up amounts including and excluding VAT, which throws off the VAT calculation. This especially goes wrong when combining products with different rates (21% and 9% on a single invoice).

We also regularly see the delivery date left out or equated with the invoice date, even though these are not always the same moment. If in doubt, state both dates separately, that avoids discussion afterwards.

What happens if an invoice does not meet the requirements?

If an invoice is incomplete, your client cannot deduct the VAT on that invoice until a correct version exists. That leads to awkward phone calls and often delays payment as well.

For repeated or structural mistakes, the Belastingdienst can question your entire set of records during an audit, even if the individual mistakes seem small. Consistency and completeness weigh more heavily than you might think.

Do you spot a mistake yourself after the invoice has already been sent? Send a credit invoice (an invoice that reverses the original one), followed by a new, correct invoice. Never quietly edit the original invoice, that breaks the sequential numbering.

How do you make sure every invoice is automatically correct?

Most mistakes happen because invoices are drawn up manually in Word or Excel, where mandatory fields are easily overlooked. A template with fixed fields prevents you from forgetting something.

A bookkeeping system built around Dutch rules automatically checks that your VAT number, KvK number and invoice number are present before you send an invoice. TelMaar does this by default, for example, so you never have to remember yourself which element is mandatory.

Do you work with clients abroad? Then slightly different rules can apply, for example around the VAT reverse charge (where your client, not you, remits the VAT). Check this per situation with the Belastingdienst or your adviser.

Frequently asked questions

Is a KvK number mandatory on every invoice?

Yes, if your business is registered with the Kamer van Koophandel, the KvK number must appear on every invoice, alongside your VAT number.

Am I allowed to change invoices retroactively?

No, you never quietly edit an invoice that has already been sent. If there is a mistake, you send a credit invoice followed by a new, correct invoice with a new number.

What if I charge both 21% and 9% VAT on a single invoice?

That is allowed, but split the amounts clearly by rate so it is clear which VAT amount belongs to which rate. Check the current rates with the Belastingdienst.

This article is general information, not tax or legal advice. When in doubt, consult an adviser; rules can change.