Voluntary Merger Notification vs No Notification in the Czech Republic (2026): When to File, Call‑in Risks and How to Decide

Every M&A team closing a deal with a Czech dimension now faces the same binary question: voluntary merger notification vs no notification in the Czech Republic, file proactively with the Office for the Protection of Competition (OPC), or proceed without notifying and accept the risk that the regulator calls the transaction in after closing. The 2025–2026 reforms to Czech merger control introduced a targeted call‑in power, updated turnover thresholds and a formal voluntary filing path, fundamentally changing the risk calculus for transactions that fall below, or sit near, the mandatory notification triggers.

This decision guide gives deal teams, GCs, CFOs and PE buyers a structured framework to make that call before signing or closing, with concrete thresholds, costs, timelines and actionable “choose X when” recommendations.

Option A: Voluntary Notification, What It Is, When It Applies, Who It Suits

A voluntary merger notification is a proactive filing with the OPC for a transaction that does not meet the mandatory notification thresholds but could raise competition concerns in the Czech Republic. Under the reformed Czech Competition Act, parties to a below‑threshold concentration may elect to notify the OPC before or after signing, triggering a formal review that, once cleared, insulates the deal from subsequent call‑in.

Legal Basis and Formality

The voluntary filing mechanism operates under the amended Czech Competition Act (Act No. 143/2001 Coll., on the Protection of Competition) and implementing Decree No. 252/2009. The notification must follow the prescribed form set out in the Decree. A filing fee of CZK 100,000 (approximately EUR 4,000) is payable to the OPC before the notification is submitted. Pre‑notification consultation with the OPC is available on a voluntary basis and is encouraged by the Office’s published guidelines, though it is not a formal prerequisite for filing.

When to Use Voluntary Filing, Practical Triggers

Voluntary notification is strategically valuable in specific deal profiles. Consider filing when:

• Horizontal overlap exists. The parties compete on the same Czech product market and the acquirer’s combined market share will be material, even though turnover thresholds are not met.
• The target is an emerging competitor. Tech and digital acquisitions, where the target has high value but low revenue, are prime call‑in candidates under the new regime.
• Deal certainty matters. Financing covenants, regulatory conditions precedent in SPAs, or buyer board requirements demand upfront regulatory clearance.
• The counterparty insists. Sellers or co‑investors may require OPC clearance as a condition to closing.

Advantages for Transactional Parties

Filing voluntarily delivers three core benefits. First, it eliminates post‑closing call‑in risk entirely: once the OPC clears the transaction, it cannot reopen the matter within the six‑month call‑in window. Second, parties control timing, they choose when to file and can manage the review period within their deal timetable rather than responding to an OPC demand at an inconvenient moment after integration has begun. Third, voluntary notification enables early remedy negotiation. If the OPC has concerns, the parties can offer commitments during a structured Phase I or Phase II review rather than facing the harsher leverage dynamics of a post‑closing investigation where the regulator holds the power to unwind or impose structural remedies after the fact.

For cross‑border transactions with multiple filing jurisdictions, a Czech voluntary notification also demonstrates regulatory discipline to other competition authorities.

Option B: Proceeding Without Notification

The alternative is to close the transaction without filing, either because the deal clearly falls below all thresholds and raises no competitive overlap, or because the parties make a strategic judgment that the cost, delay and disclosure of a voluntary filing outweigh the call‑in risk. This is a legitimate path, not a regulatory shortcut, and most below‑threshold transactions in the Czech Republic proceed this way.

Legal Baseline, When Filing Is Mandatory vs Discretionary

Filing is mandatory under the Czech Competition Act when the statutory turnover thresholds are met. If a transaction constitutes a concentration within the meaning of the Act and exceeds the merger notification thresholds in the Czech Republic, the parties have no discretion, they must file. Below those thresholds, notification is voluntary. The OPC may neither request a notification nor investigate or oppose a transaction if the jurisdictional thresholds are not met, with one critical exception introduced by the 2025–2026 reforms: the targeted call‑in power.

Practical Triggers for Proceeding Without Filing

Deal teams typically proceed without notifying when:

• Turnover is clearly below thresholds and there is no meaningful horizontal or vertical overlap in the Czech Republic.
• Speed to close is paramount, the filing process adds weeks or months that the transaction timeline cannot absorb.
• Disclosure sensitivity is high, the notification form requires detailed market data, internal documents and customer information that parties prefer not to share with a regulator absent a legal obligation.
• Low call‑in probability, the transaction does not meet the cumulative criteria that trigger the OPC’s call‑in authority.

Advantages of Not Notifying

The primary advantage is speed: no filing fee, no pre‑notification process, no review period, and no standstill obligation. Parties can sign and close on their own commercial timetable. There is also no disclosure to the regulator, the OPC receives no information about the transaction, the parties’ market positions, or the deal terms. For purely financial transactions or portfolio reshufflings with no Czech overlap, this avoids unnecessary regulatory cost. The risk is defined and bounded: the OPC’s call‑in window runs for six months from completion, after which the transaction is beyond reach. For parties with a low‑risk profile, that six‑month window represents a manageable exposure.

Voluntary Merger Notification vs No Notification: Side‑by‑Side Comparison

The following table compares the two paths across the dimensions that matter most to deal teams weighing the call‑in model vs voluntary filing in the Czech Republic.

Key takeaways from the comparison:

• Voluntary notification trades upfront cost and delay for complete post‑closing certainty.
• Proceeding without notification is faster and cheaper, unless the OPC calls the deal in, at which point costs escalate and leverage shifts to the regulator.
• The six‑month call‑in window is the critical risk variable: if the deal profile suggests the OPC is likely to exercise its call‑in power, the economics strongly favour voluntary filing.
• Deals with no Czech market overlap and turnover well below thresholds face negligible call‑in risk and gain nothing from voluntary notification.

Dimension‑by‑Dimension Analysis of Voluntary Notification vs No Notification in the Czech Republic

Eligibility and Thresholds

Mandatory notification under the Czech Competition Act is triggered when statutory turnover thresholds are met. Under the current regime, each of at least two of the parties must have turnover in the Czech Republic exceeding CZK 250 million, and the worldwide turnover of any other party must exceed CZK 1.5 billion. The 2025–2026 reforms introduced updated thresholds, the first increase in over 20 years, raising the monetary levels and modifying the treatment of joint ventures so that JVs trigger mandatory notification only where the JV itself or both of its parents generate local Czech turnover.

• Voluntary notification: Open to any transaction that constitutes a concentration but falls below mandatory thresholds. No minimum turnover required to file.
• No notification: The default when thresholds are not met. However, the OPC can now call in sub‑threshold transactions under cumulative conditions, the deal must raise suspected significant distortion of competition, and the parties’ combined net turnover must meet a lower call‑in floor.

Cost and Fees

The direct and contingent costs of each path differ materially. The table below summarises the key cost items.

The external counsel estimates reflect market benchmarks for Czech competition lawyers handling Phase I filings. Complex Phase II proceedings or post‑call‑in defence work typically command higher fees. The filing fee of CZK 100,000 must be paid before the notification is formally submitted to the OPC.

Timing and Procedural Windows

Timing is where the two paths diverge most sharply.

• Voluntary notification: The OPC’s Phase I review period runs for 30 days from receipt of a complete filing. If the case raises serious concerns and enters Phase II, the review can extend to 150 days. Pre‑notification consultations, voluntary but recommended for complex deals, add additional weeks. A standstill obligation applies: parties must not close until clearance is granted.
• No notification: No waiting period. Parties close on their own schedule. However, the OPC may call in the transaction within six months of its completion. If a call‑in notice is issued, the parties must then file and the standstill mechanics engage retroactively, the OPC can in principle require the transaction to be suspended or unwound pending review.

The practical effect is that the voluntary filing path adds 30–90+ days before closing, while the no‑notification path shifts the regulatory timeline to a six‑month post‑closing exposure window. For time‑sensitive deals, the no‑notification route is faster, unless a call‑in arrives, at which point the disruption to a completed and partially integrated transaction is far greater than a pre‑closing delay would have been.

Liability, Fines and Call‑In Risks

The risks of not notifying a merger centre on the OPC’s call‑in authority. If the Office suspects that a below‑threshold concentration may significantly distort competition and the parties’ combined net turnover exceeds the call‑in floor, it may issue a call‑in notice within six months of completion. Failure to comply with a call‑in, including failure to file after being called in, or closing in violation of a post‑call‑in standstill, exposes parties to administrative fines of up to 10% of net worldwide turnover under the Czech Competition Act. These penalties mirror the sanctions for traditional gun‑jumping in mandatory filing scenarios. Voluntary notification eliminates this exposure entirely: a cleared deal cannot be called in.

Enforceability and Remedies

The remedy landscape differs significantly between the two paths.

• Voluntary notification: Remedies are negotiated during the review. Parties can propose behavioural or structural commitments as part of Phase I or Phase II. The OPC’s leverage is moderate, the deal has not yet closed, and parties retain the option to abandon if conditions are unacceptable.
• No notification (post‑call‑in): The OPC can require structural remedies, including divestiture of businesses or assets already integrated, or impose behavioural conditions. Industry observers expect the OPC to use its post‑closing powers assertively, particularly in digital and tech acquisitions where below‑threshold targets carry strategic value. The practical cost of unwinding a completed integration vastly exceeds the cost of pre‑closing remedy negotiation.

What Changes in Czech Merger Control in 2026

The 2025–2026 reform package represents the most significant overhaul of Czech merger control since the Competition Act’s original enactment. Three changes directly affect the voluntary notification vs no notification decision:

• Targeted call‑in model. The OPC gained the power to call in below‑threshold transactions within six months of completion, provided cumulative conditions are met (suspected significant competition distortion and a minimum combined net turnover floor). This is the single most important change, it creates a new post‑closing risk that did not previously exist.
• Threshold increases. After more than 20 years, the monetary thresholds for mandatory notification have been raised. This means some transactions that previously required mandatory filing now fall below the thresholds, but remain subject to call‑in. The likely practical effect will be an increase in voluntary filings by cautious acquirers who previously filed mandatorily and now find themselves in the grey zone.
• JV treatment. Joint ventures now trigger mandatory notification only where the JV itself or both of its parents generate local Czech turnover, narrowing the scope of mandatory filing for international JV structures.

The combined effect is a more flexible but also more assertive competition authority. Deal teams should no longer assume that falling below the thresholds means no regulatory oversight. The question is whether to manage that oversight proactively (voluntary notification) or reactively (wait and see).

Decision Framework: Should I Notify the OPC or Proceed Without Filing?

This section provides the actionable framework for choosing between voluntary merger notification and no notification in the Czech Republic. Use the bullet lists below and the quick checklist to reach a decision.

Choose voluntary notification when:

• The parties have meaningful horizontal overlap or a vertical relationship on any Czech product market.
• The target is an innovative or emerging competitor with low turnover but strategic market significance.
• Closing certainty is critical, financing, board approvals or SPA conditions require regulatory clearance.
• Combined Czech turnover is close to the call‑in floor and the OPC is likely to be aware of the deal (e.g., through press coverage or third‑party complaints).
• Post‑closing integration will be rapid and difficult to reverse, making a retrospective call‑in highly disruptive.
• The deal is part of a multi‑jurisdictional filing programme and Czech clearance adds marginal cost.

Choose to proceed without notification when:

• There is no horizontal or vertical overlap on any Czech market.
• Combined Czech turnover is well below both the mandatory thresholds and the call‑in floor.
• The transaction is a purely financial investment with no change in competitive dynamics.
• Speed to close is the overriding commercial priority and a 30–90+ day review period is unacceptable.
• The six‑month call‑in window is a manageable risk given the deal’s low competition profile.

Quick checklist, decide in 10 minutes:

If two or more of the first four questions produce a “yes,” voluntary notification is the recommended path. A single “yes” warrants a competition counsel assessment before deciding. If only the fifth question is “yes,” proceed without filing.

When (and Why) to Engage a Competition Lawyer for This Decision

Not every below‑threshold deal needs counsel, but several specific situations make professional advice essential. Engage a Czech competition lawyer when:

• Turnover is near the mandatory threshold or call‑in floor, the calculation is technical, particularly for group turnover allocation, and errors are costly.
• The parties have any competitive overlap in the Czech Republic, even a modest overlap raises the probability that the OPC will exercise its call‑in power.
• The OPC issues a call‑in notice, engage counsel within 48–72 hours to assess the notice, begin preparing the filing, and manage communication with the regulator.
• The SPA contains a regulatory condition precedent, counsel should be involved before signing to assess whether voluntary filing is needed and to draft the CP appropriately.
• The deal involves a digital, tech or pharma target with low revenue but high strategic value, these are the sectors where the OPC is expected to use its call‑in power most actively.

The optimal engagement timeline is: retain counsel during due diligence (before signing) if voluntary notification is likely; immediately upon signing if threshold assessment is uncertain; and within 48–72 hours of any OPC call‑in notice. Typical engagement models include flat‑fee Phase I filings, hourly retainers for Phase II or call‑in defence, and fixed‑fee threshold assessments as a standalone service.

Sources

1. UOHS, Pre‑notification Contacts in Mergers (Official Guidance)
2. Lex Mundi, Czech Republic Merger Notification Guide
3. Havel & Partners, A New Era of Merger Control: The Targeted Call‑In Model
4. Wolters Kluwer, Czech Competition Enforcement Facing Major Changes
5. Schoenherr, Czech Republic Merger Control Guide
6. ICN, Merger Notification and Procedures Template: Czech Republic
7. Chambers Practice Guides, Merger Control 2025: Czech Republic
8. Lexology GTDT, Czech Republic Merger Control
9. Rowan Legal, Call‑In Model in Czech Merger Control