Which deadlines must you track after hiring a foreigner?

After the start you watch at least: the residence document's validity (and the 24-month oświadczenie limit), periodic medicals, the end of a fixed-term contract, carried-over leave until 30.09 (unused = an employer offence), PPK re-enrolment every 4 years (the nearest: early 2027 — opt-out declarations must be collected anew), and when the employee's child turns 18/26 — deregistration from ZCNA.

This is not a job for memory or a spreadsheet. It is a job for a system with alerts.