Bookkeeping
Taxes
The Difference Between BTW Number and BTW-ID, and When to Use Which
Confused about Dutch BTW number vs BTW-ID? Learn which goes on invoices, which is for the Belastingdienst only, and how VIES verification works.
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18 mins
Intro
Many entrepreneurs in the Netherlands experience the same confusion shortly after registering their business. A few days after their KvK registration, they receive not one, but two VAT-related numbers from the Belastingdienst. One letter contains a BTW-identificatienummer (BTW-ID), while another contains an omzetbelastingnummer (OB-nummer). Neither letter clearly explains why there are two numbers, which one belongs on invoices, or what happens if you use the wrong one.
As a result, many Dutch entrepreneurs, especially ZZP founders and first-time BV directors, have spent years using the wrong number in the wrong place. Some unknowingly placed their OB-nummer on invoices. Others provided it to European suppliers for VAT verification. Besides administrative confusion, using the wrong number can create privacy risks and compliance issues. Understanding the difference between these two numbers is therefore an essential part of running a business in the Netherlands. Entrepreneurs who are still exploring broader tax obligations should also understand how much tax you pay.
Why There Are Two Numbers: The Privacy Problem That Changed Everything
Before January 2020, Dutch entrepreneurs only had one VAT number. For sole traders and ZZP founders, this number was directly linked to their BSN (Burger Service Number). Every invoice they sent contained a number that was effectively derived from the same personal identifier used for healthcare, banking, government services, and identity verification.
This created a serious privacy issue. A freelance designer sending 60 invoices per year was effectively distributing their BSN to 60 different clients. A self-employed plumber might share their BSN with hundreds of customers over time. Criminals realised that these numbers could be collected from invoices and combined with names and addresses to facilitate identity fraud.
The introduction of the European AVG (GDPR) increased pressure on the Dutch government to address the issue. The Autoriteit Persoonsgegevens concluded that distributing BSN-based identifiers to commercial counterparties was difficult to justify under privacy legislation. As a result, the Belastingdienst introduced a new system on 1 January 2020.
The solution was simple:
The BTW-ID became the external number used with customers, suppliers, and EU authorities.
The OB-nummer remained the internal number used for communication with the Belastingdienst.
For sole traders, this represented a major privacy improvement. For BVs and other legal entities, the change was largely administrative because their identifiers are based on an RSIN rather than a personal BSN.
Entrepreneurs learning about getting your KvK number often encounter both numbers for the first time during the registration process.
The Two Numbers Explained: What Each One Is
The BTW-ID and the OB-nummer serve completely different purposes and should never be confused.
Aspect | BTW-identificatienummer (BTW-ID) | Omzetbelastingnummer (OB-nummer) |
Also known as | VAT-ID, VAT identification number | OB-nummer, belastingnummer |
Purpose | External identification with customers, suppliers and EU authorities | Internal communication with the Belastingdienst |
Goes on invoices | Yes, mandatory | No, never |
Goes on website | Yes | No |
Used in VAT returns | No | Yes |
Used in VIES | Yes | No |
Used in OSS returns | Yes | No |
Contains BSN | No (since 2020) | Yes, for sole traders |
Format (sole trader) | NL + 9 pseudo-random digits + B + 2 digits | BSN + B + 2 digits |
Format (BV) | NL + RSIN + B + 2 digits | RSIN + B + 2 digits |
Privacy risk if shared | None | High for sole traders |
Issued by | Belastingdienst | Belastingdienst |
The simplest rule to remember is:
If the number goes to a customer, supplier, website visitor, or foreign tax authority, use the BTW-ID. If the number goes to the Belastingdienst, use the OB-nummer.
There are effectively no exceptions to this rule.
Decoding the Format: What Every Component Means
Understanding the structure of both numbers makes it much easier to recognise whether you are using the correct identifier.
The BTW-ID
Example:
NL000099998B57
This format consists of three components:
Component 1: NL
The country code identifying the Netherlands within the European VAT system.
Component 2: 9 digits
For a BV or legal entity, these digits represent the RSIN.
For a sole trader, these digits are deliberately randomised and no longer reveal the BSN.
This is the core privacy protection introduced in 2020.
Component 3: B + 2 check digits
The letter B is always present.
The two digits are usually 01 for a standard registration, but can increase when additional registrations are issued.
The OB-nummer
Example:
123456789B01
This format consists of two components:
Component 1: 9 digits
For a sole trader: BSN
For a BV: RSIN
Component 2: B + 2 sequence digits
Usually B01 for the first registration.
There is no NL country code.
Quick Format Check
Number | Correct? |
NL123456789B01 on an invoice | Yes |
123456789B01 on an invoice | No |
NL123456789B01 in a VAT return | No |
123456789B01 in communication with Belastingdienst | Yes |
A BTW-ID without an NL prefix is incorrect. An OB-nummer with an NL prefix is also incorrect. Seeing an OB-nummer on an invoice is a strong sign that the wrong number is being used.
When to Use Which Number: A Complete Decision Table
Most confusion disappears once entrepreneurs understand the practical situations where each number belongs.
Situation | Use BTW-ID | Use OB-nummer | Notes |
Invoice to Dutch business | Yes | Never | Mandatory |
Invoice to consumer | Yes | Never | Mandatory |
Invoice to EU client | Yes | Never | Required for reverse charge |
Invoice outside EU | Yes | Never | Standard practice |
Quotation | Yes | Never | Recommended |
Website footer | Yes | Never | Usually required |
Email signature | Optional | Never | Common for B2B |
VAT return | No | Yes | Filing identifier |
Letter to Belastingdienst | No | Yes | Identifies your tax file |
Telephone contact with Belastingtelefoon | No | Yes | Used for identification |
OSS return | Yes | No | VIES-compatible |
VIES verification | Yes | No | Only BTW-ID appears |
Intra-community acquisition | Yes | No | Supplier checks this number |
Foreign VAT refund request | Yes | No | International authorities use VIES |
Fiscal unity VAT return | No | Yes | Filed under fiscal unity OB-nummer |
One of the most common mistakes occurs during international transactions.
When a European supplier asks for your "VAT number", they mean your BTW-ID. Providing an OB-nummer will cause the VIES verification system to return an invalid result, which may prevent the supplier from applying the correct VAT treatment.
The BV vs Sole Trader Difference: Why It Matters
The relationship between the BTW-ID and the OB-nummer differs slightly depending on the legal structure of the business.
For a sole trader or ZZP founder:
BTW-ID contains randomised digits
OB-nummer contains the BSN
Privacy protection is the main reason for the split
For a BV, NV, VOF, or other legal entity:
BTW-ID contains the RSIN
OB-nummer contains the same RSIN
No personal identifier is involved
This means that for a BV, both numbers share the same nine-digit core. The difference is primarily the NL prefix and the check digits.
Even though sharing an RSIN does not create the same privacy concerns as sharing a BSN, BVs should still never place their OB-nummer on invoices. The OB-nummer remains an internal tax administration identifier.
Entrepreneurs deciding between a BV or sole trader should understand these administrative differences alongside the broader tax and liability implications.
Getting Your Numbers: How and When They Arrive
Both numbers are issued automatically. There is no separate application process.
The process typically works as follows:
Register your business with the KvK.
The KvK forwards your registration to the Belastingdienst.
The Belastingdienst determines whether you qualify as a VAT entrepreneur.
Two separate letters are issued, one containing your BTW-ID and one containing your OB-nummer.
Both numbers usually arrive within 10 working days.
If necessary, they can also be viewed in Mijn Belastingdienst Zakelijk.
For most entrepreneurs, the process is straightforward. Businesses operating in exempt sectors such as healthcare, education, or financial services may require additional assessment before VAT status is confirmed.
Entrepreneurs who are starting a company in the Netherlands often receive both numbers shortly after completing their registration.
Additional BTW-IDs
It is possible to request an additional BTW-ID when:
Starting a separate business activity
Operating multiple locations
Managing distinct business lines
Each additional BTW-ID receives its own OB-nummer and generally requires separate VAT administration and VAT returns.
The VIES System: Verifying Your Suppliers' BTW Numbers
Any entrepreneur trading across EU borders should understand how the VIES system works.
VIES (VAT Information Exchange System) is operated by the European Commission and allows businesses to verify whether a VAT number is valid in another EU member state.
This matters because VAT exemptions for intra-community transactions often depend on using a valid VAT number.
Imagine you receive an invoice from a Belgian supplier with no VAT charged. Before processing that invoice as a VAT-exempt intra-community acquisition, you should verify the supplier's VAT number through VIES.
The process is simple:
Visit ec.europa.eu/taxation_customs/vies
Select the supplier's country
Enter the VAT number
Submit the verification
Save the result and timestamp
The timestamp serves as evidence that you performed due diligence if the transaction is ever questioned during a tax audit.
Entrepreneurs who regularly deal with cross-border transactions should also understand when to file VAT, because VIES checks form part of broader VAT compliance obligations.
Important: OB-nummers do not appear in VIES. Only BTW-IDs can be verified.
Fiscal Unity and the BTW Number: A Special Case for BV Structures
A fiscal unity for VAT purposes creates a unique numbering situation that often confuses DGA founders.
A fiscal unity usually arises when a holding BV and one or more operating BVs are financially, organisationally, and economically connected.
When a fiscal unity is approved:
The fiscal unity receives its own OB-nummer.
VAT returns are filed under this fiscal unity OB-nummer.
Each individual BV retains its own BTW-ID.
Outgoing invoices continue to show the individual BV's BTW-ID.
Transactions between fiscal unity members are VAT-free.
As a result, a DGA may see multiple VAT-related numbers within the group structure.
Entrepreneurs operating through a holding structure should understand the key differences holding BV, especially when VAT administration is consolidated across entities.
Changing Legal Form: What Happens to Your BTW Numbers?
Changing legal form usually means changing both VAT numbers.
A common example is the conversion from a sole proprietorship to a BV.
When this happens:
The sole trader registration is deregistered.
The old BTW-ID is deactivated.
The old OB-nummer is deactivated.
The new BV receives a new BTW-ID.
The new BV receives a new OB-nummer.
This has practical consequences.
Invoices issued after incorporation must use the new BV BTW-ID. Existing customers should be informed of the new VAT number so they can update their supplier records.
Using the old sole trader BTW-ID after the conversion date may require correction through credit notes and replacement invoices.
Complex conversions involving retroactive tax treatment should always be reviewed with an accountant or bookkeeper, particularly when multiple VAT periods overlap.
Make Sure You're Using the Right Number
Avoid Administrative Mistakes Before They Become Tax Problems
The difference between a BTW-ID and an OB-nummer seems small, but using the wrong number can create privacy risks, VAT compliance issues, and unnecessary administrative corrections.
At Neno, we help entrepreneurs understand not only which numbers belong where, but also how VAT, bookkeeping, payroll, and company structures fit together as your business grows.
Whether you want to incorporate your BV, improve your bookkeeping and payroll, or simply gain clarity around Dutch tax administration, our team can help.
Book a demo and discover how proactive financial management can save time and reduce compliance risk.
FAQs: BTW Number and BTW-ID in the Netherlands
What is the difference between the BTW-ID and the OB-nummer?
The BTW-ID is used externally on invoices and in international transactions. The OB-nummer is used internally for communication with the Belastingdienst.
Which number goes on my invoices?
Always the BTW-ID.
Why did the BTW-ID change in 2020?
To prevent BSN exposure and improve privacy protection under AVG regulations.
Does my BTW-ID contain my BSN?
No. Since 2020, sole trader BTW-IDs use randomised digits rather than BSN-based numbers.
How do I find my BTW-ID and OB-nummer?
Both numbers are provided by the Belastingdienst and can also be found in Mijn Belastingdienst Zakelijk.
Can I use my OB-nummer for VIES verification?
No. Only BTW-IDs are registered in VIES.
What happens to my VAT numbers when I convert from a sole trader to a BV?
Your old numbers are deactivated and your BV receives new VAT identifiers.
Do I need a VAT number if I use the KOR small business scheme?
Yes. You still receive a BTW-ID even though you do not charge VAT while participating in KOR.
What is a fiscal unity VAT number?
It is a special OB-nummer assigned to a VAT fiscal unity consisting of multiple related entities.
Can I request an additional BTW-ID for a new business activity?
Yes. The Belastingdienst can issue additional BTW-IDs when separate activities or locations require independent VAT administration.
Written by
Nick Knuppe
CEO & Founder
