Advocaten / Avocats / Lawyers

Friday, 24 December 2021

International Tax Update: Dear tax administration: what you don’t publish can be used against you – but not against the taxpayer

How the MLI enters into effect between Belgium and the Netherlands, but is not opposable to the Belgian taxpayer (yet)

In our previous international tax update we already indicated that the Belgian-Dutch double tax treaty will be covered by the MLI, and have highlighted some of the main changes this entails. As stated, this will enter into force on January 1st 2022 for withholding tax purposes. Belgium and the Netherlands opted for a shorter period (than the normal period of 9 months) for the MLI’s entry into force for other taxes as well. To this effect, they stealthily made an additional notification to the OECD, so the MLI would already apply for taxable periods starting on or after January 1st 2022, instead of only for taxable periods starting on or after 25 August 2022 (i.e. 9 months after both notifications made on 25 November 2021).

Further analysis now points out that the Belgian tax administration has taken its wishes for granted.

For whereas the MLI may enter into force for taxable periods starting on or after January 1st 2022, this does not mean that this earlier entry into force is also opposable to Belgian taxpayers. In this case, Belgian constitutional grounds indeed impose a contrary conclusion. In other words, the Belgian tax authorities may not and cannot invoke it for taxable periods starting before 25 August 2022.

The main reasons for this are the following:

  • A jurisdiction’s reservations and notifications are an integral part of the MLI and must, as a rule, be submitted to the different Belgian parliaments involved. Without their explicit consent, these cannot become part of the Belgian domestic legal order. Art. 3 of the law of April 7th 2019 (regarding the adoption of the MLI) provides that amendments to the reservations and notifications made, would have full effect. This would be an anticipatory assent to a future treaty amendment, which in Belgium is only accepted under strict conditions. These are not met as far as Belgium’s additional notification of 25 November 2021 is concerned. This notification, significantly and for the first time reducing the entry into effect of the MLI to a Belgian tax treaty, has therefore not received the constitutionally required legislatures’ assent. One may think ‘Dura lex sed lex’, but it is just – plain and simple – the application of our democratic Constitution that has been in place for about 190 years.

  • Second, Belgian citizens cannot be bound by rules they have not been properly made aware of. For this reason, these rules must be published in the Belgian Gazette, after which publication citizens are considered to ‘know the law’. For reservations and notifications to the MLI made by other states, such as the Netherlands, the publication thereof on the website of the OECD is exceptionally considered to suffice. This, however, is explicitly not the case for Belgium’s own notifications and reservations. After having received all necessary legislatures’ consents, these have to be published in the Belgian Gazette. Moreover, the additional notification from Belgium (concerning the reduced period for the Belgian-Dutch treaty to enter into force) has to date only been published in French on the OECD website. Belgian citizens, however, have to be notified of the rules that are to govern them in their own, official language. As less than 50% of Belgians live in an area where the official language is French, this requirement is also not met.


  • From an international legal point of view the MLI indeed enters into effect as of 1 January 2022;

  • The MLI rules regarding withholding taxes will be opposable to Belgian taxpayers and have to be complied with for payments as of 1 January 2022;

  • The reduced period for the MLI’s entry into force regarding this tax treaty, is not opposable to Belgian taxpayers;

  • Without a timely rectification of the above mentioned constitutional deficits to the Belgian notification, the MLI provisions such as the principle purpose test will not yet govern Belgian taxpayers’ legal situation for taxable periods commencing before 25 August 2022.

If you are or think you might be confronted with issues regarding this new development in a Belgian-Dutch cross-border situation, please do not hesitate to contact any of the people below.

Rik Smet - Associate (

Jacob Huyzentruyt - Associate (

Tiberghien’s international tax team will continue to monitor these and other tax developments relevant for Belgium / Luxembourg based multinational enterprises. Our editorial board consists of: 

Koen Morbée (International and EU corporate tax,;

Michiel Boeren (International and EU corporate tax,;

Ahmed El Jilali (International and EU corporate tax,;

Katrien Bollen (HR tax and global mobility,;

Ben Plessers (Transfer Pricing and Valuations,;

Gert Vranckx (VAT, customs, excises and other indirect taxes,

Rik Smet (International and EU corporate tax,


In case you have further questions on this publication or want to discuss a tax query, please do not hesitate to contact the author(s) or one of the members of the editorial board. 

This newsflash is for information purposes only and cannot be relied upon as legal advice.

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