March is the month when increased attention should be paid to the deadlines for filing tax returns and tax reconciliations. In the following article, we focus on the key deadlines you should not overlook to ensure that your tax obligations are met properly and on time.

Withholding tax reconciliation – deadline: 1 April 2026

Withholding tax must be calculated and paid by the deadline for filing the reconciliation. If you withheld tax during 2025, you must file the reconciliation by 1 April 2026. This may concern, for example, authors’ fees, dividends, profit shares, or royalty payments.

The reconciliation is filed by the tax remitter separately for taxes withheld from taxpayers who are individuals and for taxpayers who are legal entities. If the tax remitter pays, remits, or credits payments both to individuals and to legal entities, two separate reconciliations must be submitted.

Personal income tax return – deadline: 1 April 2026

The 1 April 2026 deadline is binding for all individuals filing their 2025 tax return in paper form. By this date, they are required not only to file the return, but also to pay the tax. The standard three-month deadline for filing a tax return is also traditionally important for taxpayers seeking to obtain a tax refund as soon as possible. If they file both the tax return and the refund request by 1 April 2026, the tax administrator will refund the overpayment no later than 4 May 2026.

The deadlines for filing income tax returns for the 2025 tax period are as follows:

• paper filing: by Wednesday, 1 April 2026
• electronic filing: by Monday, 4 May 2026
• filing through a tax adviser or for taxpayers subject to a mandatory statutory audit of their financial statements: by Wednesday, 1 July 2026

Windfall profits tax return – deadline: 1 April 2026

Certain entities that generated windfall profits in 2025 are required to file a windfall profits tax return. Windfall profits tax is a separate corporate income tax. Apart from a different tax base calculation and tax rate, the same provisions apply as for standard corporate income tax, including the deadlines for filing the return.

All of the above deadlines are important for the proper fulfilment of your tax obligations. It is therefore crucial to prepare for them in advance. If needed, do not hesitate to contact the PKF APOGEO tax team — we will help you avoid mistakes in the preparation and filing of your return or reconciliation.

For filing personal income tax returns, you can also use our online smart form Dáňa, which guides you through the entire process and ensures that nothing is missing.
Dáňa is designed for all individuals who want to complete their tax return within a few minutes while also having confidence that everything is filled in correctly and in line with current legislation. It is most commonly used by self-employed individuals, employees with additional income, and people who want to handle their taxes independently, but with professional support.

A helping hand is also available through our tax AI chatbot an online AI assistant that provides answers within seconds, helps you while completing the form, and works with an up-to-date and verified database prepared by tax advisers, helping you avoid outdated or incorrect information.

Notification of exempt income: a deadline that is often overlooked

Individuals who received a single exempt income exceeding CZK 5,000,000 in 2025 are required to notify the tax administrator of this fact. This obligation applies regardless of whether the individual is otherwise required to file a tax return.

The deadline for filing the notification is the same as the deadline for filing the tax return for the relevant tax period. For the 2025 tax period, this will generally be 1 April 2026, 4 May 2026 for electronic filing, and 1 July 2026 for filing through a tax adviser or attorney, or in cases involving a mandatory audit. The notification must always include the amount of income, a description of the circumstances in which it was acquired, the date the income arose, and the reason for the exemption.

The notification does not have to be filed if the tax administrator can obtain the relevant information from records or registers to which it has access and which are published in the manner prescribed by law. However, it is not advisable to assume that this exception automatically applies in every case, which is why we recommend filing the notification in almost all cases. Failure to comply with the notification obligation may trigger penalties amounting to 0.1%, 10%, or 15% of the unreported income, depending on when, and whether at all, the taxpayer fulfils the obligation. We therefore recommend assessing the notification obligation separately and in good time for income exceeding CZK 5 million, rather than treating it as a secondary issue when preparing the tax return.

Do you need help with filing your tax return so that everything is done correctly and on time? Do not hesitate to contact us, together, we can file your tax return easily and quickly.

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