JMHZ in Practice: First Experiences and Most Common Mistakes

The Unified Monthly Employer Report (JMHZ) under Act No. 323/2025 Coll. has been a reality for all employers in the Czech Republic since April 2026. The first regular report for April was due on May 20, 2026, and June 30, 2026 was the deadline for retroactive reports covering January to March. What have the first months of live operation shown?

- During April 2026, employers submitted supplementary registration data on all employees to ČSSZ - The first regular JMHZ (for April 2026) was due May 20, 2026 - Retroactive reports for January to March 2026 had to be submitted by June 30, 2026 - Reports continue monthly, always by the 20th day of the following month Reports are submitted electronically to ČSSZ — via payroll software integration (API), the web portal jmhz.mpsv.cz, or a data mailbox.

1. Forgotten agreement workers and directors JMHZ also covers work-performance agreements (DPP), work-activity agreements (DPČ), and directors with remuneration — including non-financial remuneration such as a company car for private use. Companies used to reporting only "core" employees easily forget these groups. 2. Merged concurrent relationships If one person has both an employment contract and an agreement with the same employer, each relationship must be reported separately. Merging them into one record leads to errors in assessment bases. 3. Incomplete registration data Monthly reports build on the supplementary registration data submitted in April. If registration was not completed for all employees (typically short-term agreements), the monthly reports won't reconcile. 4. Data format and validation Data must comply with the technical specification (XML). Older or non-updated payroll software generates files that fail validation — and the problem is often discovered just before the deadline. 5. Underestimating the 20th-day deadline The deadline is fixed and JMHZ data is used by multiple institutions at once (ČSSZ, Financial Administration, Labour Office, Czech Statistical Office). An error or delay therefore shows up in several places simultaneously.

1. Close payroll inputs as soon as possible after month end — attendance, bonuses, deductions 2. Set an internal submission deadline several days before the 20th 3. After each submission, check the acceptance confirmation and any error logs 4. Keep your payroll software up to date — the technical specification may be refined 5. Continuously review your records of agreements and concurrent employment relationships

If you have not yet submitted the retroactive Q1 reports or any monthly report, we recommend submitting them as soon as possible without waiting for an official notice — penalties apply for non-submission or late submission.

As an external payroll provider, we submit JMHZ on behalf of our clients as part of regular monthly payroll processing — the client supplies the inputs and we take care of formats, validation, and deadlines. If your company is struggling with JMHZ, get in touch — we'll prepare a non-binding payroll takeover quote within 48 hours. Official information and technical documentation are available at jmhz.mpsv.cz and the ČSSZ website.