Income tax return: which deadline applies to you

There is not one deadline but three, and the one that binds you depends on how you file and who files it. Since a data box is standard for sole traders, most people are on the electronic date.

Deadline: 1 April · 2 May · 1 July

Paper, electronic and tax-advisor deadlines for the previous tax year. A date falling on a weekend moves to the next working day.

Open the flat-tax calculator

Three deadlines

The basic deadline is three months after the end of the tax period. Filing electronically buys a month, and a tax advisor or a statutory audit buys three.

Paper return: three months after the year ends, so 1 April.
Electronic return: four months, so 2 May, which is the date for anyone filing through the tax portal or a data box.
Tax advisor with a power of attorney on file, or a statutory audit: six months, so 1 July.

Who has to file

Filing is not only for sole traders. The thresholds catch employees with income on the side, and they are lower than people expect.

Anyone whose annual income subject to income tax passed 50 000 CZK.
An employee whose income outside employment passed 20 000 CZK, which also removes the employer annual settlement.
Anyone with taxable employment income from two employers at the same time.
Anyone reporting a tax loss, and anyone whose flat-tax regime failed a condition during the year.

Paying and advances

The tax is payable on the day the return is due, not later, and the return itself sets the advances for the following year.

The balance is due on the last day of your filing deadline.
No advances at all when the last known liability stayed at or below 30 000 CZK.
Up to 150 000 CZK you pay two advances of 40 %. Above that, four advances of 25 %.

Filing late

There is a short grace period, after which the fine grows daily. Paying late is charged separately from filing late.

Five working days of delay carry no fine at all.
After that the fine is 0.05 % of the assessed tax for each day of delay, and it is only charged once it passes 1 000 CZK.
Late payment carries interest on top, counted from the day after the tax was due.

Common questions

Does my data box change the deadline?

Yes. A return sent through a data box or the tax portal is an electronic filing, so your deadline is 2 May rather than 1 April. Sole traders have had a data box set up by law since 2023, which is why the electronic date is now the normal one.

Can I move to the 1 July deadline after 1 April?

Yes, as long as the power of attorney for the tax advisor reaches the tax office before your original deadline expires. Filing the power of attorney afterwards extends nothing.

I have a job and rent out one flat. Can my employer settle my tax?

Not once your income outside employment passes 20 000 CZK for the year. You file your own return, put the rent in the §9 attachment and ask the employer for a certificate of taxable income.

See the year before the deadline

The flat-tax calculator compares the regimes for the same income, so you know which return you are filing before the deadline arrives.