Dutch CIT fiscal unity with retroactive effect: the 3-month rule

A Dutch CIT fiscal unity can take retroactive effect, but the window is strictly capped. The request must reach the Belastingdienst within three months of the desired consolidation date (article 15(9) Dutch CIT Act 1969). File later, and the unity either starts later than you wanted, or does not take retroactive effect at all.

What does the law say exactly?

Article 15(9) Dutch CIT Act 1969 provides that the request for a fiscal unity must be filed within three months of the moment the fiscal unity is deemed to have come into existence. That moment is the consolidation date: the date you choose as the starting point of the unity. The three-month window therefore runs backward from the filing date, not forward from the consolidation date.

Example: if you want the unity to start on 1 January 2026, the request must reach the Belastingdienst by 1 April 2026 at the latest. File on 15 April 2026 instead, and 1 January 2026 is no longer available as the consolidation date; the earliest date available is three months before the actual filing date, or the filing date itself, depending on what you request.

How is the three-month window counted?

The Belastingdienst counts in calendar months, not days. Three months back from 31 May is 28 February (29 February in a leap year), not a fixed number of days such as 90 or 92. When months have a different number of days, the resulting date is rounded down to the last day of the shorter month. Do not count by days; count back by calendar month from the intended filing date.

Example: BV Parent and BV Subsidiary want to consolidate as of 31 May 2026. The request must then be filed by 31 August 2026 at the latest (three calendar months later). Conversely, if you file on 15 July 2026, 15 April 2026 is the earliest possible consolidation date with retroactive effect.

Why is the deadline so strict?

The three-month window is a hard deadline, not one that can be extended for special circumstances. Missing it does not block the fiscal unity itself, only the desired start date. You can still file a request, but with a later consolidation date: at the earliest, three months before the new filing date.

This matters most for acquisitions and reorganisations around year-end. If a subsidiary is acquired on 1 December and you want the unity to start that day, the window closes on 1 March of the following year. Wait longer to file, and you lose alignment with the full financial year, which can create a broken financial year for the CIT return.

A practical approach

• Fix the desired consolidation date as early as possible, for example right after a share transfer or incorporation.
• Calculate the filing deadline using calendar months, not a day count.
• File well before the deadline: the Belastingdienst must actually have received the complete, signed request, not merely have had it sent.
• Check the other requirements of article 15 Dutch CIT Act before filing; see Requirements for a Dutch CIT fiscal unity 2026.

Difference with the VAT unity

The VAT fiscal unity has no comparable retroactive-effect rule: that unity arises by operation of law once the interlinkage is met, and the inspector's ruling applies going forward, not retroactively. Do not confuse the two regimes; read the difference in CIT fiscal unity vs VAT fiscal unity: what is the difference?.

Next step

More on the regime as a whole: What is a Dutch CIT fiscal unity?. Run the eligibility check to see whether your group meets the requirements, and work out which filing date matches your desired consolidation date before you prepare the request.