Act quickly: don't miss important tax deadlines in December 2025

Tip 1: Disclose annual financial statements for 2024 by December 31, 2025, at the latest

Companies with the legal form of a GmbH, AG, or GmbH & Co. KG are subject to disclosure requirements. Annual financial statements must be submitted to the electronic business register to be submitted.

For most companies, the fiscal year corresponds to the calendar year. The financial statements for 2024 must then be submitted by December 31, 2025, at the latest. This deadline cannot be extended! Anyone who submits late will face penalties. It is irrelevant that companies receiving tax advice still have until April 30, 2026, to submit their 2024 tax returns (due to the extension of the regular filing deadline).

Tip 2: Apply for loss certificates for capital income by December 15, 2025

The stock market offers both opportunities and risks. Investments in stocks or funds can therefore also result in losses. These cannot be offset against other income, but they can be offset against stock gains. In this case, no withholding tax is payable on the stock gains. Offsetting only works automatically if all stock purchases and sales are processed through the same credit institution.

If the losses were incurred at a different credit institution than the profits, a loss certificate is required. The loss certificate must be actively requested. Without this, it is not possible to offset stock losses against stock gains in your tax return, and the bank will carry forward the loss offset pool to 2026.

Note:
Please note the application deadline—you must apply for the loss certificate from your bank by December 15, 2025, at the latest. The same applies here: There will be no extension of the deadline!

Tip 3: Keep track of social security contribution deadlines

Employers are obliged to calculate and pay their employees' wages on time. They must withhold income tax and social security contributions, report them to the tax office or social security collection agencies, and pay them. There are also deadlines to be observed here. Total social security contributions are always due on the third-last banking day of the month in which the employment is carried out. For December 2025, these are due on December 23, 2025, due to public holidays, weekends, and non-banking days (December 24 and 31). This applies both to social security contributions that you, as an employer, have to pay to the respective social security collection agencies and to contributions from voluntarily insured persons. However, the contribution statements for the month of December must already be submitted by December 19, 2025.

Tip 4: Submit voluntary tax returns for 2021 by December 31, 2025

Not all employees are required to file a tax return. Even though it always involves a certain amount of effort, in many cases it is worth filing an income tax return voluntarily. Additional income-related expenses, other special expenses, or expenses for household-related services or craftsmen's services often result in a tax refund. You have up to four years to submit a so-called application assessment. This means that a tax return for 2021 can be submitted until December 31, 2025.

Note:
If you are required to file a tax return, e.g. because you received short-time work benefits, sick pay, or parental allowance last year, or because you have other income, the deadline for filing your tax return for 2024 has already passed and you may face late filing penalties. However, if you are represented by a tax advisor, you have until April 30, 2026.

Tip 5: Avoid the statute of limitations on outstanding claims

Do you have defaulting payers and outstanding claims from 2022? Then you should check whether an impending statute of limitations at the end of the year can be postponed with legal dunning proceedings. In everyday business, a 3-year statute of limitations generally applies, beginning at the end of the year in which a claim for action or omission arose. This means that all outstanding claims from 2022 for which there are no court collection proceedings, lawsuits, or acknowledgments of debt will become time-barred on December 31, 2025. If there are claims arising from so-called continuing obligations, e.g., from tenancies, the statute of limitations must be checked for each individual claim. If you are unsure about how to deal with impending statutes of limitations, you should seek legal advice.