What happens to my single permit if I lose my job in Poland?

The single permit is granted on the basis of a specific job, so ending that employment changes the circumstances on which the permit was issued. This does not always mean instant loss of status, but it is a significant change that you should not ignore.

You should inform the relevant authority of the change and look at your options, which may include finding new qualifying employment and amending or reapplying for a permit. Acting quickly gives you the best chance of staying lawfully in Poland, whereas doing nothing risks your residence permit being withdrawn.