The tax year in Poland is the calendar year that consists of twelve consecutive months ending on December 31. However, a limited liability company or a stock company is free to change its tax year by choosing another twelve-month period and notifying the competent tax office.
The company is obliged to file yearly corporate income tax declaration to the tax authorities until the end the of 3rd month of its fiscal year's following year (usually it is end of March).
The deadline for filing the annual PIT return is April 30th.
The monthly VAT return must be submitted to the tax office by the 25th day of each month for the previous month and the quarterly VAT return must be submitted by the 25th day of month after end of the quarter for the previous quarter.