Filing a tax return is part of everyday life for many people—yet there is often uncertainty about who is required to file and which deadlines apply. The key distinction to understand first is between mandatory and voluntary filing.
Deadlines for mandatory submission and for voluntary tax returns
Anyone who is required to submit a tax return must generally file it with the tax office by 31 July of the following year. For the 2025 tax year, the deadline is 31 July 2026. If a tax advisor or a wage tax assistance association is engaged, the deadline is significantly extended: for 2025, it then runs until 1 March 2027.
The situation is much more relaxed for those who file voluntarily. In these cases, the 31 July deadline does not apply. Instead, taxpayers have up to four years to submit their return—unless they are explicitly requested to do so by the tax office.
Special aspects of cross‑border cases
However, in cross-border situations, there is often an obligation to file. If you reside in Germany, you are in most cases required to submit a tax return in Germany. If you reside in the Netherlands or Belgium, this obligation usually does not apply to non-resident taxpayers. However, if an application for unlimited tax liability is submitted, a tax return must also be filed.
Important documents and practical guidance
Regardless of the deadline, good preparation is essential. This includes, in particular, your tax number, tax ID, wage tax certificates or pension documents, as well as proof of additional income and deductible expenses. Keeping your documents complete and well organized saves time and helps avoid follow-up questions from the tax office.
Special attention is required if you have income from abroad or combine multiple activities. Working from home can also have tax implications for frontier workers — that is, when your place of residence and place of work are in different countries. In such cases, taxing rights may partially shift, which is why carefully documenting working days is advisable. Please find here more information regarding tax implications of frontier workers’ remote working between Germany and the Netherlands.
For employees residing in the Netherlands or Belgium, the tax office responsible for the permanent establishment of the employer is generally competent, while for pensioners living abroad, the tax office in Neubrandenburg is responsible.
Support with filing a tax return is available through the free online portal ELSTER provided by the tax authorities, as well as through tax advisors and wage tax assistance associations (Lohnsteuerhilfeverein). Please note, however, that online tools and apps are generally not well suited for cross-border situations. For more complex or international cases, individual advice can help avoid errors.