Reminder: Croatia to Replace Fiskalcis Certificate on September 8, 2026

Reminder: The Croatian Tax Administration announced on August 4, 2026 that the Fiskalcis application certificate will be replaced on September 8 at 5:00 a.m. The new public key will be available from September 1, giving retailers and POS providers one week to prepare their systems.

This is a reminder of the Croatian Tax Administration’s notification originally published on August 4, 2026, concerning the upcoming replacement of the Fiskalcis application certificate used within Croatia’s fiscalization system.

The replacement is scheduled for September 8, 2026 at 5:00 a.m., meaning that affected retailers, POS providers and fiscalization software vendors should now ensure that their systems are prepared for the change.

The public key of the new Fiskalcis certificate will be available from September 1, 2026, through the FINA certificate search service and the Croatian Tax Administration’s website.

Although the original announcement was published more than a month before the replacement, the practical implementation window is significantly shorter because the new public key becomes available only seven days before the production switch.

What exactly is changing?

The Fiskalcis certificate should not be confused with the application certificate used by a taxpayer to sign its own fiscalization requests.

Within the Croatian fiscalization process, the taxpayer’s fiscalization solution sends an XML request to the Tax Administration. The Tax Administration processes the request and returns an XML response, which is electronically signed using its Fiskalcis application certificate.

After receiving the response, the taxpayer’s fiscalization solution should verify that electronic signature using the public key of the Fiskalcis certificate.

The purpose of this verification is to confirm that the response genuinely originates from the Croatian Tax Administration and has not been altered during transmission.

Therefore, the September change concerns the certificate used to establish trust in responses coming from the Tax Administration. It does not introduce a new fiscal receipt, change VAT calculation, transaction numbering or the standard content of fiscalized receipts.

Why does this matter for POS systems?

A POS or fiscalization solution that continues to rely only on the old Fiskalcis public key after September 8 may experience problems validating responses signed with the new certificate.

The exact consequence will depend on how the particular fiscalization solution is designed. For example, a system could successfully send an invoice to the Tax Administration and receive a valid response, but then fail local signature verification because it still trusts only the previous certificate.

Depending on the implementation, this could lead to signature-validation errors, technical alerts, unnecessary retries or problems with processing fiscalization responses and the returned JIR.

This does not necessarily mean that every affected POS would immediately stop issuing receipts. The practical behavior depends on the architecture of the fiscalization solution and its handling of communication or validation errors.

However, relying on fallback mechanisms is not an appropriate migration strategy. The new certificate should be correctly implemented before the production switch.

Who is impacted?

The change is relevant to businesses subject to fiscalization in final consumption in Croatia, while the technical implementation will usually be handled by POS providers, fiscalization software vendors, retailers’ IT departments or other service providers responsible for fiscal communication.

The actual scope of the update depends on the system architecture.

Where verification is performed centrally through fiscalization middleware or a backend service, the new public key may only need to be deployed centrally.

Where individual stores, POS devices or local fiscalization components maintain their own certificate stores, the update may need to be distributed across multiple endpoints.

This can be particularly relevant for larger retailers operating many stores, different POS versions, legacy solutions or decentralized fiscalization components.

Importantly, the August 4 notification concerns the Tax Administration’s Fiskalcis certificate. It does not state that retailers need to replace their own taxpayer application certificates as part of this specific change. Those certificates have their own validity periods and should be managed separately.

Why is this reminder important now?

The timing is particularly relevant.

The Tax Administration provided advance notice on August 4, 2026, but the new public key will only become available on September 1, while the actual replacement takes place on September 8 at 5:00 a.m.

This leaves POS providers and affected businesses with an effective one-week deployment period once the new certificate becomes available.

For a centrally managed fiscalization solution, implementation may be relatively simple. For retailers with a large number of POS endpoints, several software versions or locally maintained certificate stores, deployment may require more coordination and testing.

For this reason, the original August notification should now be treated as an implementation reminder, not simply as an informational announcement.

What should retailers and POS providers do?

Retailers and POS providers should first determine where the Fiskalcis public key is stored and which component verifies the Tax Administration’s electronic signature.

Once the new public key becomes available on September 1, it should be obtained from an official source and deployed to the relevant production components before September 8.

For larger retail environments, this may include checking:

• central fiscalization services and middleware,
• store-level POS systems,
• local certificate stores,
• different POS software versions, and
• legacy fiscalization components.

Monitoring should also be increased around the September 8 production switch, particularly for signature-validation errors and unusual issues with processing JIR responses.

From our perspective, this is primarily a technical maintenance requirement rather than a new fiscalization obligation. Nevertheless, certificate validation is part of the secure communication between taxpayers’ systems and the Tax Administration, so failure to prepare the fiscalization solution could lead to operational issues even though the underlying fiscal rules are not changing.

The main action is therefore clear: the announcement was published on August 4, the new public key becomes available on September 1, and affected systems should be updated and ready before the Fiskalcis certificate is replaced on September 8 at 5:00 a.m.

The main official source is the notification published by the Croatian Tax Administration on August 4, 2026, announcing the Fiskalcis certificate replacement. Source

Filip Kalaba, Junior Legal Consultant at Fiscal Solutions