PIT means a personal income tax. It is collected both from Polish tax residents and from persons who do not have a Polish tax residence. In this second case, the tax is collected only from revenues that were obtained in Poland.
You must settle the tax due in each tax year. For this purpose, the employee receives PIT-37 from the employer. This declaration should be settled by the date indicated by the tax office. You can settle both electronically and directly at the tax office to which you belong.