6.75% tax surcharge? Not for those who pay on time!

For your company, it is crucial to make advance payments throughout the year against the tax ultimately due. Those who fail to do so, or do so insufficiently, risk a tax surcharge imposed by the tax authorities. For assessment year 2027, that surcharge—just as for assessment year 2026—is 6.75%. By comparison, in assessment year 2025 it was still 9%. However, 6.75% remains a significant cost when no (sufficient) advance payments are made. It is therefore essential to keep a close eye on the deadlines and take timely action.

Advance payments

To avoid a tax surcharge, it is necessary to make advance payments—the earlier, the better, given the related credits (see below). These payments reduce the tax surcharge, depending on when they are made.

For companies with a calendar financial year 2026, the following deadlines apply:

• Advance payment 1: no later than 10 April 2026
• Advance payment 2: no later than 10 July 2026
• Advance payment 3: no later than 12 October 2026
• Advance payment 4: no later than 21 December 2026

For companies with a non-calendar financial year, different dates apply: the advance payments must then be made no later than the tenth day of the fourth, seventh and tenth month, and the twentieth day of the last month of the financial year.

Each advance payment generates a benefit that is deducted from the 6.75% tax surcharge. This benefit decreases as the financial year progresses:

• Advance payment 1: 9%
• Advance payment 2: 7.50%
• Advance payment 3: 6%
• Advance payment 4: 4.50%

The average of these percentages corresponds to the 6.75% tax surcharge. If you make sufficient advance payments, the benefits fully offset the surcharge. If too much has been paid, the excess will be refunded.

The first advance payment (10 April 2026) is the most advantageous. A payment of approximately 75% of the estimated corporate income tax by that date is usually sufficient to avoid the tax surcharge. From the third quarter onwards, the benefit is lower than the 6.75% surcharge. It is therefore advisable to make most of the advance payments via the first two instalments.

Example: Assume the tax due amounts to EUR 20,000; the tax authorities will then apply a 6.75% surcharge if no advance payments have been made. Consequently, the standard surcharge amounts to EUR 1,350. If an advance payment of EUR 15,000 was made in the first quarter, the surcharge can be reduced by EUR 15,000 x 9% (i.e., EUR 1,350), thereby fully neutralising the tax surcharge.

Important: note that in corporate income tax you can never obtain a true additional discount on the tax in the form of a credit for making advance payments.

Exceptions to the tax surcharge

10% tax when allocating to a liquidation reserve

If you allocate your company’s profit (after corporate income tax) to a so-called liquidation reserve, you pay corporate income tax of 10% on it. This additional tax has no impact on the tax surcharge.

Exemption for new companies

Newly incorporated small companies are exempt from advance payments and the related tax surcharge during their first three financial years following incorporation.

Tax shelter as an alternative to advance payments

Your company can also choose to invest in a tax shelter. This scheme encourages the production of audiovisual works (films, series) and stage productions. A correctly calculated tax shelter investment reduces the taxable base, meaning you owe less tax. In addition, the investment often provides a financial benefit in the form of interest.

Our PKF BOFIDI experts are here to help

It is essential to pay sufficient advance payments on time in 2026 in order to avoid a tax surcharge. Do you need help calculating your advance payments? Then contact your file manager.

Are you considering an investment via a tax shelter? Our experts can also support you with targeted advice!

This article was written by Emma Degrande, Fikret Seven and Stijn Schalck