Taxes
I Filed an Incorrect Tax Return – What Now?
· 3 min read
A mistake in a tax return is corrected in two different ways depending on whether the statutory filing deadline is still running. The distinction is crucial for potential penalties.
Short answer
YES
Yes, the error must be corrected. The required procedure depends solely on one question: has the statutory deadline for the original tax return already expired?
Quick take
- Before the filing deadline expires, you submit a corrective tax return (opravné daňové přiznání) — it fully replaces the original filing with zero penalties.
- After the deadline passes, you must submit a supplementary tax return (dodatečné daňové přiznání) by the end of the month following the discovery of the mistake.
- If the correction results in higher tax, late payment interest accrues, but reporting it voluntarily avoids heavy audit penalties.
- It is always better to report an error before the tax authority uncovers it during a tax audit.
Corrective return — before the deadline expires
You submit a new, complete tax return marked as a corrective return (opravné daňové přiznání). The tax authority disregards the previous filing entirely and processes only the most recent submission. This is the cleanest option without any penalties, which is why it pays to file tax returns early rather than on the final day of the deadline.
Supplementary return — after the deadline has passed
You must file a supplementary tax return (dodatečné daňové přiznání) if the corrected tax liability is higher, or optionally if you are claiming a lower tax liability. The deadline is the end of the month following the month in which you discovered the error, and any tax shortfall is payable within that exact same timeframe. In the supplementary return, you report only the difference compared to the last assessed tax liability.
Sanctions and late payment interest
On any additional tax assessed, late payment interest (úrok z prodlení) accrues from the original due date. However, if the tax administrator reassesses the tax during a tax audit, a 20% penalty (penále) is added automatically — which is why voluntary correction is always much cheaper. If the correction results in lower tax, a refundable overpayment arises.
Do not forget subsequent filings
For self-employed individuals (OSVČ), a change in the income tax base also requires submitting amended annual overviews (přehledy) to OSSZ (Czech Social Security Administration) and your health insurance provider. For corporate entities, adjustments may affect the statutory financial statements and their publication in the Commercial Register's Collection of Documents.
What to do now
- 1Check whether the standard filing deadline has passed — choose a corrective or supplementary return accordingly.
- 2File the correction and pay any resulting tax shortfall within the same deadline.
- 3Submit amended annual overviews to OSSZ (Czech Social Security Administration) and your health insurance company.
When to call an accountant
For errors spanning multiple tax years, issues involving tax losses, asset depreciation, or reserves, and whenever a tax audit is already underway.
Frequently asked questions
- Can I file a supplementary tax return for a lower tax liability?
- Yes, provided statutory conditions are met. The resulting overpayment can be refunded or transferred to offset another tax balance.
- How long do I have to correct a tax return?
- Generally throughout the tax assessment limitation period, which is standardly three years, though this can be extended under specific legal circumstances.
- What happens if the tax office discovers the error first?
- You can no longer file a voluntary supplementary tax return, and a mandatory penalty (penále) of up to 20% will be added on top of the reassessed tax shortfall.
Sources
Author: FinTaxo expert team
Operated by: Zaklipso s.r.o.
Information valid as of: 17 August 2026
Czech original: read this article in Czech
This article is general information and does not replace individual tax, accounting or legal advice. Czech legislation changes frequently — verify the current wording or discuss your situation with us before acting on it.
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