Short answer
CIT (podatek dochodowy od osób prawnych) is Poland's corporate income tax. The standard rate is 19%. A reduced 9% rate applies to "small taxpayers" and businesses starting operations, generally where annual revenue doesn't exceed roughly 2 million euros (converted to PLN).
What this depends on
The 9% rate applies to operating income only -- capital gains are taxed at 19% regardless of small-taxpayer status. The reduced rate also has restrictions (for example, it generally doesn't apply to companies formed through certain transformations or capital-group structures).
Documents / steps
Companies file an annual CIT return by 31 March (or within three months of their fiscal year-end) and pay monthly (or quarterly, for qualifying smaller businesses) advance payments throughout the year, by the 20th of each month.
Important exception
Poland also offers an alternative "Estonian CIT" regime, where tax is generally paid only when profits are distributed -- a different mechanism that can result in a different effective rate depending on your situation.
Official source
Podatki.gov.pl and Biznes.gov.pl, directly verified. Generally speaking -- confirm the exact current rate and threshold with a qualified accountant before relying on it for filing.
Need assistance?
This is general information, not personalized tax advice. For individual guidance, consult a qualified accountant or tax adviser, or start an enquiry with Auranik.