Flat Tax 2027: Deadlines and How to Decide This Year

The flat tax (paušální daň) is typically dealt with in January, at the last minute and under stress. Yet whether it will pay off for you in 2027, and which band you can even enter, is determined by your income for the whole of 2026. The second half of the year is therefore the ideal time for an interim stocktake: you already know roughly how much you'll earn this year, and you still have room to influence the situation. In this article, you'll find the key deadlines for 2027, the entry conditions, and a practical procedure for deciding in advance.

Key Deadlines: Everything Hinges on 10 January 2027

According to the Financial Administration's general information on the flat tax, the following deadlines apply to changes in the flat-rate regime:

• Entering the flat-rate regime for 2027: you file the notification no later than 10 January 2027. Anyone starting a business during the year can file the notification as of the day they begin their activity.
• Voluntary exit from the flat-rate regime: also by 10 January of the year following the tax period, i.e. by 10 January 2027, if you want to switch back to filing a tax return in 2027. A notification filed after the deadline is ineffective and you remain in the regime for the entire next year.
• Changing bands: possible only as of 1 January, by notification within the same deadline. Bands cannot be changed during the year.
• Advance payments due: always by the 20th day of the calendar month.

Who Can Enter the Flat-Rate Regime

The Financial Administration summarises the entry conditions for 2027 as follows:

• you are self-employed (OSVČ) under the social and health insurance acts,
• you are not a VAT payer and have no VAT registration obligation,
• you are not a partner in a general partnership or a general partner in a limited partnership,
• you are not in insolvency proceedings,
• your income from self-employment for the previous year (i.e. for 2026) did not exceed the limit decisive for the given band.

The last point is precisely why the decision-making is happening now. The limit counts income for the whole of 2026, and the structure of that income determines which band you fit into.

The Three Bands and Current Advance Payments

Watch out for two things. First, the Band 1 advance changed during 2026: an amendment retroactively lowered pension contributions for the self-employed, so from July 2026 the advance is 9,162 Kč instead of the original 9,984 Kč, and taxpayers accrued an overpayment of 4,932 Kč for the first half-year, as stated in the Financial Administration's press release. A detailed procedure for handling the overpayment is in our article on the reduction of self-employed advances from July 2026.

Second, the advance amounts for 2027 have not yet been announced. The insurance components of the advance are derived from the average wage for the given year, which the government sets each autumn. So watch the Financial Administration's website for the specific 2027 figures once they are officially published. For decision-making, though, it's usually not the amounts to the exact koruna that matter, but the structure of your income and possible deductions.

What to Base Your Decision on in the Second Half of 2026

A detailed comparison of the two regimes, including model situations, is in our article flat tax vs. tax return.

When It Makes Sense to Consider Exiting

The flat-rate regime is great for administration: no tax return, no statements for the ČSSZ (Czech Social Security Administration) or the health insurance company. Even so, there are situations where it pays to file a notification of voluntary exit by 10 January 2027:

• You've had a child or your family situation has changed. The child tax credit and the spouse credit cannot be claimed in the flat-rate regime.
• Your income has fallen. With low profit, tax in the classic regime can come out at zero, while the flat-rate advance stays the same.
• You've taken out a mortgage or are saving significantly for retirement. Deductions for interest and contributions reduce the tax base only in the classic regime.
• You expect a loss-making year. A tax loss can be declared and used only outside the flat-rate regime.

Conversely, if you have stable income without large deductions and value freedom from forms, there's no reason to change anything. You remain in the flat-rate regime automatically; no notification is filed to continue. Just make sure you didn't exceed your band's limit in 2026; exceeding the decisive income means an obligation to change bands, or possibly leave the regime.

Conclusion: January Starts in Summer

The 10 January 2027 deadline looks distant, but the decision leading up to it rests on the numbers for the whole of 2026. Anyone who does their stocktake in summer or autumn has time to calculate both options calmly, perhaps still influence the structure of their income, and in January simply send off a ready-made notification.

The foundation of any such calculation is order in your income and expenses throughout the year. That's exactly what DokladBot helps with: photograph a document in WhatsApp, it processes and records it, so you always have an up-to-date income overview at hand and can compare the flat tax with reality in a few minutes.