Polish Labour Code (Art. 129: Standards and length of working time)
Working time may not exceed 8 hours in a 24-hour period and an average of 40 hours in an average five-day working week in an applicable settlement period not exceeding four months. In every working time system, if it is due to objective or technical or work-organization related reasons, the settlement period may be prolonged up to 12 months while observing the general standards of protecting employees‘ safety and hygiene.