Since December 21, 2007, Poland is part of the Schengen Area, a zone without controls on internal borders which comprises of 28 countries. Third-country nationals may enter Poland if they are in possession of a valid travel document and a visa (if required). Council Regulation (EC) No 539/2001 includes the lists of third countries whose nationals must possess valid visas to cross external borders, and of countries whose nationals are exempt from this obligation.
Citizens of many countries outside the European Union who wish to enter Poland are required to hold a visa, which is to be obtained at the Polish consulate before leaving. Visas are of the following categories: transit visa of 'A' category (only for transit through Polish territory within the airport), Schengen visa of 'C' category (entitles you to stay in Poland or Schengen-zone countries for 90 days within half a year, as of the date of your first entry), national visa of 'D' category valid for the duration spanning from 90 days to 1 year.
Third-country nationals are allowed to enter Poland and stay there if they are in the possession of one of the following documents:
The validity of the Polish long-stay national visa (D) does not exceed one year.
The requirements for third-country nationals entering the Schengen Area are governed by the Community Code on Visas.
To enter the territory of a Schengen State, third-country nationals must be in possession of a valid travel document and a visa (if required). They must also meet the following requirements:
After undergoing border control, it is possible to move freely within the Schengen Area. Schengen States issue the following types of uniform visas which entitle the holder to enter and stay in the Schengen territory:
Apart from uniform visas, Schengen states issue national long-stay visas (D) and residence permits.
Holders of residence permits and national long-stay visas (D) issued by one of the Schengen states are allowed to travel within the Schengen Area during a maximum of three months within a six month period.
The visa application should be submitted to and examined by the relevant consular post in accordance with its territorial competence. Applicants should contact relevant consular post in order to obtain the application as well as information on the electronic registration of the application and visa fees. The application will be examined no later than 15 calendar days after the date of submission of the full set of documents.
Polish delegations are not present in some countries. In this case, the applicant is obliged to submit the application to the relevant Polish consular post in another country, or in another Schengen consulate which represents Poland in visa matters.
Source: Ministry of Foreign Affairs of the Republic of Poland (13 February 2018)
More information: http://www.msz.gov.pl/en/travel_to_poland/entering_poland/