Short summary
- Belgium’s 2026 tax filing season is now open for income earned in 2025
- Key deadlines: 30 June (paper), 15 July (standard online), 16 October (complex returns)
- Expats and taxpayers with foreign income or self-employment must file carefully
- Filing via a tax advisor allows deadline extension until October 2026
Tax Season in Belgium Has Started
If you lived in Belgium in 2025 or arrived in the country last year, you have likely received an online notification from the Belgian authorities that your 2025 tax return can be submitted. Tax-on-web, the platform to file your taxes online, is available from 28 April onwards.
The 2025 return covers the period between 1.01.2025 and 31.12.2025, unless you arrived later in the year or have left Belgium before the year-end. While the online tax form can soon be submitted, the paper form (‘brown envelope’) is still on the way and should arrive in your mailbox in the next few weeks.
Traditionally, Tax-on-Web remains accessible until 15 July 2026. for filings that do not include foreign income and/or self-employed business income. If you would still prefer the traditional method of filing on paper, the form will normally mention a filing deadline.
Filing deadlines for 2026
This year, the tax filing deadline depends on the type of earnings and the complexity of the return.
| DEADLINE | Standard filing | Complex filing |
| On paper | 30 June 2026 | 30 June 2026 |
| Online | 15 July 2026 | 16 October 2026 |
A tax filing is considered complicated if it includes one or more of the following types of income:
- Company director remuneration
- Self-employed income
- Business income
- Foreign earned income
More taxpayers will receive a so-called ‘tax return proposal’ this year as well, based on the info that is readily available by the tax authorities. It is a noble attempt to facilitate the filing process, but often contains errors. It is therefore useful to check it and not simply accept what is mentioned in the pre-completed return. For example, foreign earnings and business income will never be included in the proposal, so this would always require your personal input.
Watch Out for Errors in the Tax Return Proposal
If you need more time to prepare your filing or prefer to delay paying your taxes, you can file through an accountant or tax advisor who is able to submit online until 16 October 2026 (if your filing for 2025 can be considered complicated). As the online filing system often experiences errors and irregularities, the Belgian authorities might extend the deadline, but that traditionally happens the very last minute.
Need More Time for Tax Filing? File Through a Tax Advisor
If you do not agree with the ‘tax return proposal’, you or your tax advisor only have time to respond until 15 July 2026, so the standard filing extension until October does not apply here.
If you need professional help to prepare your 2026 tax return, your foreign bank account reporting and/or foreign real estate reporting, do not hesitate to reach out to us!
Key Takeaways
- Always verify your tax return proposal – errors are common, especially for foreign income
- Use Tax-on-Web for faster, more flexible filing and extended deadlines, and avoid the paper filing form, if possible
- Paper submissions close on 30 June 2026 – no exceptions are allowed
- If you disagree with the ‘tax return proposal’, you must act before 15 July 2026
- Filing through a tax advisor gives you extra time and helps to avoid mistakes
- Expats in Belgium should pay special attention to foreign bank accounts, foreign real estate, and foreign income reporting