On 25 September 2026, the FPS Finance officially announced the postponement of two major tax deadlines: Biztax declarations move from 30 September to 15 October 2026, and personal income tax declarations with specific income from 16 October to 31 October 2026.
This decision follows consultation between the ITAA, the cabinet of Finance Minister Jan Jambon and the administration, in response to technical difficulties encountered on the tax platforms.
Two new dates to remember
Biztax declarations (corporate tax, legal entities tax and non-residents tax/companies) can now be submitted until 15 October 2026, whilst personal income tax declarations including specific income (profits, directors' remuneration, assisting spouses or foreign professional income) benefit from an extension until 31 October 2026.
The choice of two separate dates reflects operational logic: according to the FPS Finance, concentrating several deadlines on the same day increases pressure on the platforms at the most critical moment. The staggered approach aims to preserve continuity of service.
A context of repeated technical pressures
These postponements are not insignificant. The Belgian State was formally notified by the federation of accountants and tax advisers due to repeated outages of the FPS Finance IT platforms, including a major outage of MyMinfin and Tax-on-web in mid-July 2026.
The persistent technical difficulties encountered within the tax platforms have regularly put the online declaration tools under severe strain in recent months. An initial postponement had already been granted in July for simple personal income tax declarations, moved from 15 to 19 July 2026.
A reduced but appreciated working margin
For fiduciaries and company directors, these additional 15 days constitute a limited but real breathing space. As at 16 September 2026, 316,646 declarations had already been submitted via Biztax, more than 10% higher than the previous year according to FPS Finance figures.
That said, the 15 October deadline is fast approaching. For files that cannot be finalised within the deadlines due to force majeure or serious reasons, it remains possible to request an additional extension from the FPS Finance — including via a grouped request if several clients are affected by the same reason.
Our recommendation
Do not consider these new dates as a target, but as a safety net. The earlier you file, the less you contribute to saturating the platforms as deadlines approach. Filing early presents no disadvantage: a declaration submitted earlier does not bring forward a possible audit, as confirmed by Finance Minister Jan Jambon.
At AgiFid, we encourage our clients to finalise their declarations as quickly as possible. The extended deadline is a safety measure, not an invitation to wait.
If your file requires close support or if you wish to manage your tax affairs more smoothly on Odoo, contact us: free discovery call, 5-step process, coordinated follow-up with Agitech for technical integration.