Unified Monthly Reporting in Practice

What JMHZ means for your company and payroll software

The Unified Monthly Report (JMHZ) is not just another form invented by state authorities. It represents a fundamental change in how a company communicates with public administration and manages its employees' data.

Until the beginning of April 2026, your company likely submitted dozens of individual reports to various institutions – for example, pension insurance records to ČSSZ, income data to the Financial Administration, social security reports, information on employees with disabilities to the Labour Office, and many others. Each report had a different form, format, and deadline, and the same information was often repeated across the data.

From April 2026, everything is centralized into a single electronic report, which is submitted monthly by the 20th. Given that the employer bears responsibility for the correctness of levies and labor law data, it may be useful to continuously consult the setup of internal processes in the area of employment law. day of the following month.

The report has three basic parts: a summary section with basic company details and financial data, an insurance section with social security and health insurance contributions, and an individualized section with information on each employee separately – start date, termination, sick leave, parental leave, and the like.

This system means that your payroll software must not only be able to calculate and tax wages, but also export data in a precisely defined XML format so that the ČSSZ ePortal can receive and process it.

This is where the first critical point arises: many payroll software systems used by companies were not originally prepared for JMHZ. Some older systems, commercial solutions from small vendors, or custom-made in-house solutions – all these systems need an upgrade, customization, or a completely new module.

If your software is not ready, you basically have several options: invest in its modernization, buy a new one, or temporarily export data manually and edit it in a spreadsheet editor. None of these options is ideal, which is precisely why more issues are being resolved in these weeks than employers expected. The practical impact on HR agenda (including records and remote work arrangements) is also summarized in the follow-up text on working hours tracking during home office.

What technical and data requirements JMHZ places on payroll software

If you feel that your existing software should be compatible with JMHZ, the first step is to find out what that actually means. JMHZ is not a simple table export – it is a structured data format with precise rules based on regulations and methodological guidelines of the state administration. The software generating the report must meet a wide range of technical and content requirements.

Most importantly, the report is submitted exclusively in XML format through the "Submission by uploading data from the accounting system" service on the ČSSZ ePortal. This means your software must have a feature that allows you to export data into XML files, which you then upload to the ePortal.

Old methods, such as printing to PDF and manually filling out a web form or pasting a table into Excel, do not work here. The ePortal does not accept these formats, and the report will not be submitted. If the format and content of exports also raise the question of contractual guarantees and supplier liability, it is advisable to rely on legal support in the area of contracts and negotiations.

The second critical layer is the structure and content of the data. JMHZ must contain a number of mandatory fields with precisely defined formats and scopes. These include, for example, the employee identifier, their personal identification number (rodné číslo) or tax ID, the month for which the report is submitted, the amount of income, withheld taxes, insurance contributions, applied discounts, results of the annual tax reconciliation, and similar.

When the software exports data containing an error in any of these fields – such as an incorrect date format, an invalid character, or a missing mandatory value – the ePortal will reject the report and return a list of errors. The specific impacts of changes on agreements and related levies are also analyzed in the news article Agreements on completing a job (DPP) in 2026: how to correctly set limits, prevent unexpected tax levies and penalties after changes to the Labor Code.

The third layer is the link to the employee register. Every employee included in the report must be registered in the ČSSZ system and have their basic details correctly filled in. If the software exports data for an employee who is not in the register or whose identifier is missing, the report will not be processed. This means the software must have access to data from the employee register and must be able to communicate with the ČSSZ ePortal or at least verify that the employee identifiers in the report are valid.

The fourth layer is the management of multiple adjustments and corrections during the month. In real practice, it happens that during the month you find out you calculated someone's wages incorrectly, an employee went on sick leave, or insurance rates changed. The software must allow making corrections and submitting updated reports without damaging the integrity of the data in the system.

Typical data errors and their impact on reporting

Looking at the real reports that started arriving at ČSSZ from April 1, 2026, specific errors most frequently appear, leading to rejection or a request from ČSSZ for correction. It is important to know what these are so that your software and your communication with the vendor are directed the right way.

The most common error is unfilled mandatory fields. The report contains dozens of fields, many of which are mandatory – they must always be filled in. These include the employee identifier, their personal identification number or ID, the month for which the report is submitted, the amount of income, the amount of insurance contributions, and many others. If any of these fields remain empty, the ePortal will reject the report and return an error message.

Therefore, the software must have built-in validation to check that all mandatory fields are filled in before the report is even exported. The second group of errors consists of unauthorized or incorrectly filled fields. The report also contains some fields that should only be filled in certain cases or have fixed defined values.

If the software fills in something that should not be there at all, or enters a value that is not in the list of allowed values (codebook), the report is rejected. An example is the sick leave type field – if the software enters a value not defined in the ČSSZ system, the report will contain an error.

The third group consists of incorrect combinations of identifiers. Each report must contain the correct combinations of the company's ID (IČO) and its identifier in the ČSSZ system (employment ID), or the identifiers of payroll offices. If the software exports a report with an ID (IČO) that does not match the employment ID or the registration of the payroll office, the report will be processed incorrectly or not accepted at all.

The fourth group consists of formatting errors and character encoding. The XML format requires precise encoding and the use of allowed characters. When the software exports data containing special characters (diacritics) that are not correctly encoded, the XML becomes invalid and the ePortal will not accept it.

If any of these errors occur, ČSSZ will usually warn you first and give you time to correct them. However, if the errors persist or there are too many of them, penalties may apply – ČSSZ can impose a fine, deny the effectiveness of the report (meaning your insurance contributions will not be recognized), or prevent you from making further submissions. In extreme cases, the matter may escalate to administrative proceedings or penalties.

Key points in communication with your payroll software vendor

If you already have existing payroll software and need to communicate with its vendor about readiness for JMHZ, it is important to know what to ask and how to ensure you get precise answers. Many vendors are not used to providing the declarative and legally binding answers you need now.

Clear plan and readiness schedule

The first step is to ask the vendor what their plan is for JMHZ and when the system will be ready. They should give you a specific date by which the functionality will be available. Ideally, this should be earlier than May to give you time for testing.
If the vendor responds vaguely ("it will be soon", "we are working on it", "we are discussing it"), it is a warning sign. Ask them to reply in writing. Once you have a specific deadline in an email or an updated price list, you have it documented and can refer to it later if it is not met.

Detailed description of functionality

The second step is to ask what exactly the software will do. They should be able to describe to you that it will export XML in the precise format defined by ČSSZ and that it will validate the data before export.

Furthermore, it should be able to generate reports for multiple payroll offices separately (if you have them), handle corrections and report updates, and support all the data you must report (start date, termination, sick leave, taking leave, etc.). Request detailed documentation – ideally a manual or specification of what the software can and cannot do.

Testing and operation conditions

The third step is to plan how you will test the functionality. You should agree with the vendor that during March and April 2026, it would be possible to test the export on the ČSSZ test server or in a sandbox.

Furthermore, that you will be able to export dummy or real reports and verify that the ePortal accepts them without errors. Many vendors offer a testing period – take advantage of it. If the software fails during the test, that is the time to fine-tune it, not to panic during live operation in May.

Support and SLA

The fourth point is to ensure that the vendor will provide support during the critical phase. Ideally, you should have a contact for technical support available to you during April and May, with a reasonably short response time (for example, within one working day).
If the vendor is a small company or a freelancer, it is extra important to make sure they are available. If they tell you they are only available via the web or only respond on Fridays, it is not a good sign.

Update obligation and additional features

The fifth point is to clarify what happens if the state administration issues further guidelines or changes the format. MPSV and ČSSZ have already issued methodological letters several times, specifying details about JMHZ. If the vendor releases new software or an update, they should provide it free of charge (or at least for a reasonable price) if the changes are caused by a change in state regulation. Make sure you have this agreed upon.

Liability and review options

The sixth point is to make sure you have the option to get a refund or purchase services elsewhere if the software does not work. This is often addressed in the purchase agreement.
General law (Act No. 89/2012 Coll., Civil Code) gives you certain rights regarding product defects, but it is better to have this explicitly agreed in the purchase or license agreement. The Prague-based legal team at ARROWS law firm can help you review the contract with your vendor and ensure your rights are sufficiently protected – consultation@arws.cz.

Practical steps in communication with the vendor – checklist

To help you structure your communication with the vendor, here is a practical checklist of what you should manage during April 2026:

• By the end of March 2026: You should have contacted your payroll software vendor to ask how prepared they are for JMHZ. Request specific information regarding the deadline, functionality, and testing possibilities. Order the update if it is not part of your current package, or arrange a demo of new software if you are deciding to purchase.

• Beginning of April 2026: If you have access to the ČSSZ test server, start testing the export. If it is not available, ask the vendor for a simulation – i.e., to generate a sample XML file for you that you could validate manually. Check if the export is in order and if these reports are accepted.

• Second half of April 2026: Submission of the first reports for the month of March. Carefully monitor what the ePortal returns. If the report is accepted without errors, it is a good sign. If error messages are returned, analyze them immediately and inform the vendor. Ask them to fix the software and test again.

• End of April 2026: At the last minute, you should know whether the software is (or is not) ready for regular operation in May. If everything is in order, you can rest. If you are not sure, it is not too late to buy new software or arrange emergency support from your vendor.

New records and employee identifiers – what this means for your software

In addition to the JMHZ export itself, the legislative change also introduced new records and identifiers. This means your software must now also work with new data fields and systems that it did not have to previously. Specifically, each employee is now assigned a unique identifier in the ČSSZ system, which is used for all reports, registrations, and communication.

Your software must therefore be able to work with this identifier – it may already have it loaded from the employee register, or it must be able to request or import it. If the software was not able to use this identifier in the past, it must do so now.

The second layer is that JMHZ introduces new categories of data that you did not have to report before or reported differently. These include, for example, detailed data on the employee's work and health capacity, data on withheld taxes, data on the use of social benefits, or data on corrections made to levies from previous years. The software must be able to manage and export all this data into the report.

The third layer is that if you have multiple payroll offices, each of them submits reports separately. If your software previously worked with a centralized database of all employees, it must now be able to logically separate data by individual payroll offices and export them in separate files. If your software does not have all these features, or has them but incorrectly, it will result in errors during the JMHZ export. This is precisely why it is so important to test it before live operation.

Schedule and preparation time – what is not managed on time will be a problem

Since the launch of JMHZ on April 1, 2026, a very specific schedule has been in place that companies must monitor. If you do not understand something or if things do not go according to plan, delays will occur that will haunt you for months. The period from March 1 to March 31, 2026, was intended for employers to verify employee records with ČSSZ, add new identifiers, and prepare for the new system.

This means that right now (in mid-April), you should be in the final phase of this preparation. If you missed it, you should catch up by the end of April before it is too late. From April 1, 2026, employers are obliged to submit monthly reports. This means that the first report submitted under live operation is the report for the month of March, which is submitted in April.

If you have the software ready and the report is error-free, everything is fine. If there are errors, ČSSZ will notify you and you will have time to correct them. From May 1, 2026, employers must submit the report for the month of April by May 20th (i.e., the "standard" deadline: from the 1st to the 20th day of the following month). This is already the regular regime – there is no slowing down or explaining here. If you do not submit the report, you face penalties.

From January 1 to March 31, 2026, employers were not obliged to submit monthly Unified Monthly Employer Reports (JMHZ) within the standard deadlines. This is part of the transitional regime. For the months of January to March 2026, employers must retroactively submit monthly reports in the period from April to June 2026 if they had employees in those months.

This means that in May, the company will submit reports both for April (standardly) and potentially for any of the months from January to March (if these reports have not yet been retroactively submitted), which is slightly more complex. The key idea is: the preparation time is shortest right now. The months of May and June are already live operation. If something is not ready, it will have impacts for years.

Security aspects and data protection

JMHZ works with sensitive personal data of employees – their personal identification numbers, income, tax data, health information (sick leave, maternity leave). When the software exports the report, it should be ensured that this data is protected securely.

Specifically, this means that communication between your software and the ČSSZ ePortal should be encrypted (SSL/TLS). Furthermore, logging into the ePortal should be protected by a strong password or two-factor authentication.

Exported XML files should not be archived in unsecured locations (for example, on unencrypted flash drives).

If your software cannot do this, or if you are not sure that the data is sufficiently protected, you should also address security aspects with the vendor. This is not just an IT problem – it is also a legal issue. Under Czech legislation (GDPR regulation), the provider or operator of the software must choose appropriate security measures.

If data were to be misused due to insufficient software security, the company that prepared the software could be held liable. This is another argument for communicating clearly with the vendor and ensuring they have clearly defined security requirements.

Customers, entrepreneurs, and those responsible for HR – what you should know

If you work in the HR department, the finance department, or are responsible for communicating with vendors, you should now know this:

In a word – preparation for JMHZ is happening now. It is not something you can leave for later. The most important thing is to communicate with your payroll software vendor now (in April), find out how prepared they are, and expect that you might need to buy new software, additional features, or external IT support.

In two words – the responsibility lies with the company, not the vendor. If the report contains errors, ČSSZ will ask you to correct them and potentially impose a fine. The software vendor does not share this responsibility (unless you explicitly agree so in the purchase contract). Do not use this as an excuse – rather, spend time ensuring the software works correctly.

In three words – testing is free and essential. If you have access to ČSSZ test servers, use them. If not, at least request sample exports and verify their correctness. This testing can save you from a crisis.

In four words – in April 2026, there is no longer time for major changes. If you buy new software or make major changes now, you will have perhaps only weeks for testing. If you put it off until May, it will be too late.

The Prague-based legal team at ARROWS law firm can help you negotiate the vendor contract, formulate software requirements, analyze risks, and, if things go wrong, also legally resolve disputes with the vendor – consultation@arws.cz.

Final Summary

The Unified Monthly Employer Report is historically the greatest simplification of Czech administration – instead of dozens of forms, just one. But this also means that this single form must be absolutely correct. If you mess up one report, it is worse than when you previously had ten different forms and one had an error.

Right now, in the second half of April 2026, you are in the middle of a critical period. Companies that are prepared are starting to submit their first reports, and everything is running smoothly. Companies that are not prepared are experiencing chaos – their software cannot export, the ePortal returns errors, and they do not know what to do.

Your communication with the payroll software vendor is the most important factor at this moment. If you are clear about what you want from them, if you have it agreed in the purchase contract, if you have conducted testing and know the issues, then you have the prerequisites for success. If you have any doubts, now is the time to ask and resolve the matter with experts.

The Prague-based legal team at ARROWS law firm deals with these issues in practice – helping companies align with software vendors, analyze risks, provide legal defense in case of failure, and in the transitional phase, also communicate with ČSSZ. If you are unsure how to proceed, or if you are already having problems with your software, contact us – consultation@arws.cz. Together, we can audit your readiness status and create a plan to safely navigate the critical months ahead.