Deadlines for filing personal income tax returns change again

Jana Iterbeke   |  

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The deadlines for filing an annual personal income tax return (aka personal income tax declaration) have already changed several times over the years, often creating a lot of uncertainty for taxpayers. As of assessment year 2023, income year 2022, some more changes have been introduced. We list the most important ones below.

“Complex” declaration

Until last year, a longer filing period was granted for all personal income tax declarations filed by a mandatary. For tax returns relating to assessment year 2023, however, this criterion has been dropped. From now on, filing deadlines will be based on a new criterion, i.e. the nature of the income and the complexity of the declaration. A longer filing period will be granted to returns that contain one or more of the following types of income, and can therefore be considered complex:

  1. Profits and/or income from professions
  2. Executive remuneration
  3. Remuneration paid to assisting spouses/legal cohabitants
  4. Foreign professional income.

Consequently, returns that do not contain any of the above income will not benefit from a later deadline, whether filed by a mandatary or not.

However, we are expecting a royal decree laying down additional definitions for complex returns. For example, what about returns involving foreign moveable income? Or a Cayman tax analysis? While cases like these do not fall into any of the categories above, these declarations are also very complex. One might also wonder what people should do if they only discover after the first filing deadline that theirs is not a complex return after all. Will it be possible, in such cases, to invoke force majeure for late filing?

Important dates

Personal income tax returns for income year 2022, assessment year 2023, should be filed no later than:

  • 30 June 2023, for returns filed on paper, whether or not they are complex;
  • 15 July 2023, for filing non-complex returns via Tax-on-web;
  • 18 October 2023, for filing complex returns via Tax-on-web;
  • 15 January 2024 for flat rate returns.

To encourage prompt filing of complex returns, taxpayers who file their returns before 1 September 2023 will be rewarded. They will be reimbursed faster or given longer to pay than taxpayers whose returns are filed between 1 September and 18 October 2023.

What about simplified declaration proposals?

In a simplified tax declaration proposal, the tax authorities simulate the tax calculation based on the tax data that they know. If some things are missing or do not tally, they can still be added and/or changed. Additions and changes are also subject to the deadlines previously mentioned, i.e. 30 June 2023 for returns filed on paper, and 15 July 2023 for returns via Tax-on-web.

If the simplified declaration proposal needs to be amended by the addition of one or more incomes that make the declaration complex, the taxpayer or their mandatary must request an extension of the amendment period by 15 July 2023 at the latest. Then the declaration can be filed via Tax-on-web by 18 October 2023 at the latest.


Since assessment year 2023, the following general principle applies: the filing deadline for personal income tax returns depends on the complexity of the return. Ordinary returns must be filed on paper by 30 June 2023 at the latest, or by 15 July 2023 via Tax-on-web. Complex returns can be filed until 18 October 2023. However, we are still waiting for additional clarification regarding the term ‘complex tax return’, as this currently raises many questions.

Our Bofidi experts will be happy to help you

Do you have any other specific questions on this topic? Then please do not hesitate to contact Jana. Our team of Bofidi experts will be happy to provide you with more help.