Income tax deadlines for the self-employed in 2026

 

Tax office return

Put simply, there are 3 deadlines for filing an income tax return:

(*) The tax office allows a small grace period for payments up to 5 working days late; interest starts accruing after that. 

The first two deadlines fall within the statutory period, and you can choose either freely. The latest deadline is a special case requiring a power of attorney for a tax adviser, who then files the return in their own name through their own data box. This “deferral” of the tax payment costs around CZK 5,000. 

 

Statements for health insurers and the OSSZ

Once you have chosen when to file your tax return, you can decide when to submit your health and social insurance statements. They must be submitted no later than 1 month after filing the return. Any amount due must be paid within 8 days of submission. 

As you can imagine, there are many possible combinations for filing the return and statements. Generally, choose according to when you would prefer to pay the tax and any insurance shortfalls. 

 

Overpayments 

You may also have an overpayment of tax or insurance. Refund deadlines differ considerably, depending on the institution and when you filed the return or statement.

 

Income tax advance payments to the tax office

Filing timing affects not only tax and insurance payments but also subsequent advance payments. Income tax is probably the most complicated case. Self-employed people whose last known tax liability exceeded CZK 30,000 must make advance payments. Depending on the tax amount, they pay half-yearly or quarterly.

For the first two standard tax payment deadlines, the first advance payment is due in June. With the latest filing deadline through a tax adviser, both the tax payment itself and the first advance payment are deferred: to 15.9. for quarterly advances or 15.12. for half-yearly advances.

 

Health insurance and OSSZ advance payments

Advance payment amounts change from year to year, and you need to make sure that from January you always pay at least the minimum advances. The statements you submit are then used to calculate the advances you will pay until you submit the following year’s statements. Essentially, you update your advances based on last year’s income to minimise underpayments or overpayments. It is similar to electricity bills: your supplier also increases your advances if your most recent consumption was high. 🙂

For a health insurance statement, you must adjust your advance payments from the month in which you submit it. For a social insurance statement, you only adjust them from the following month.

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There are many options, and their impact on your cash flow can be enormous. In general, though, I see 3 types of clients. They may give you some inspiration:

1. Those who want everything paid immediately and do not wait for any deadline. We submit everything as soon as it is prepared and approved.
2. Those who want to delay payments as much as possible without paying for the privilege. The return is filed in late April, with tax due on 4.5.2026. We submit statements in late May, and payment falls around the turn of May and June. 
3. Those who really want to defer payments and pay for an extension through a tax adviser. The return is filed in late June, with tax due on 1.7.2024. We submit statements in late July, and payment falls around the turn of July and August. 

 

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When would you like to file? 🙂 If you are not sure which option is best for you, get in touch with us and we will look at it together. We will make sure you do not get lost in the accounting jungle. 🌿