The tax authority cannot assess tax indefinitely. In Slovakia the right to assess tax generally lapses five years after the end of the year in which the return was due, never exceeding ten years even after interruptions. In the Czech Republic the basic assessment period is shorter — three years — but it can be extended and interrupted up to a ten-year ceiling. Collecting an already-assessed debt is a separate deadline: six years in both countries.
What is the assessment period and how does it differ from prescription?
Both countries run two distinct clocks. The assessment period (prekluzívna lehota in Slovakia, lhůta pro stanovení daně in the Czech Republic) limits how long the authority may assess or reassess tax; once it expires, no audit can lead to additional tax, and the authority must respect this on its own. The collection period applies only after tax has been assessed but left unpaid, limiting how long the debt can be enforced.
The distinction matters most for businesses on both sides of the border, which need two separate compliance calendars rather than one, as our Slovak tax advisory overview explains. A tax year that has closed in one country may still be open in the other.
How long is the basic assessment period?
In Slovakia tax cannot be assessed after five years from the end of the year in which the obligation to file the return arose; since 1 January 2022 this five-year period applies uniformly to most taxes. In the Czech Republic the basic period is three years, running from the day the deadline for the ordinary return expired.
Example: for 2025 income tax, the Slovak clock runs from the end of 2026 and closes on 31 December 2031, while the Czech clock runs from the April 2026 filing deadline and closes in April 2029. The same tax year therefore stays open two years longer in Slovakia than in the Czech Republic.
How do tax losses affect the period?
The two countries diverge here. In Slovakia, a special seven-year period for loss years was abolished from 1 January 2022, so the uniform five-year period now applies to loss years as well. In the Czech Republic, by contrast, a tax loss ties the assessment period for the loss year to the last year in which the loss may be used — up to five following periods — so it can stretch well beyond three years. A Czech supplementary return or notice filed in the last twelve months adds a further one year.
Can an audit reset the clock?
In both systems an audit resets the clock: a Slovak assessment step or a Czech tax inspection starts the period running again from scratch. Each qualifying step can therefore push the deadline several years further out, which is why an old year is not necessarily as closed as it looks.
Both systems nevertheless share the same hard ceiling — the right to assess tax ends after ten years at the latest, no matter how many times it was interrupted. Ten years is the final line that no further step by the authority can cross.
How long can the authority collect an assessed debt?
Once tax is validly assessed but unpaid, the collection clock starts. In both countries a tax debt can no longer be enforced after six years — measured in Slovakia from the end of the year the arrears arose, and in the Czech Republic from the due date. Enforcement steps such as a payment demand or a seizure interrupt this period and start it again.
The absolute limit is twenty years in both countries, extended in the Czech Republic to thirty years where the debt is secured by a registered lien. One Slovak peculiarity is worth remembering: the authority does not apply prescription automatically — the taxpayer must raise it as a defence, or the debt can still be pursued.
How can you keep track of your own deadlines?
Two habits protect you in either country. First, keep your records for at least as long as the assessment period runs — five years in Slovakia and three in the Czech Republic, and longer where an audit has interrupted the clock or a Czech tax loss extends the period. Even a correctly declared tax is hard to defend without documents.
Second, watch prescription on old debts: if the authority revives years-old arrears, check whether the collection period has already lapsed, and in Slovakia raise the defence yourself. Sound bookkeeping makes all of this routine, which is where professional accounting for companies earns its keep.
Not sure whether an older tax year is still open, or whether you face an audit or debt collection in Slovakia or the Czech Republic? We will review your deadlines, assess the risk of assessment and collection lapsing, and prepare your records so you are ready for any inspection.
FAQ
How far back can a tax audit go?
In Slovakia an audit can lead to additional tax within five years of the year the return was due; in the Czech Republic the basic period is three years. Starting an audit resets the clock, but in both countries the right to assess tax ends after ten years at the latest.
What is the difference between the assessment and collection periods?
The assessment period limits how long the authority may assess or reassess tax (five years in Slovakia, three in the Czech Republic). The collection period limits how long an already-assessed debt can be enforced (six years in both). They are separate clocks with different start dates and lengths.
How long should I keep tax records?
Keep them at least for the length of the assessment period — five years in Slovakia, three in the Czech Republic — and longer if an audit interrupted the clock or, in the Czech Republic, if you claimed a tax loss, in which case holding them toward the ten-year ceiling is prudent.