Here is the list of documents which are appropriate for be treated as a proof of language skills (please ask if the certificate you own is not listed here):

Document issued abroad recognized as equivalent of secondary school leaving certificate if English was the language of instruction.

Evidence of completion of higher education or post-graduate work done abroad (or in the Polish Republic) in English as the language of instruction, only if the language of instruction was the only foreign language.

Certificate confirming knowledge of English language issued by the appropriate Ministry in Poland as a result of linguistic examination.

Certificates confirming knowledge of English language at least on level B2 according to the „Common European Framework of Reference for Languages: learning, teaching, assessment (CEFR) – European system Reference for Languages: learning, teaching, assessment (CEFR)”.

Certificates issued by institutions affiliated the Association of Language Testers in Europe (ALTE) – levels of ALTE Level 3 (B2), ALTE Level 4 (C1), ALTE Level 5 (C2), in particular Certificates:

• First Certificate in English (FCE)
• Certificate in Advanced English (CAE)
• Certificate of Proficiency in English (CPE)
• Business English Certificate (BEC) Vantage — at least Pass
• Business English Certificate (BEC) Higher
• Certificate in English for International Business and Trade (CEIBT)

Educational Testing Service (ETS) — in particular Certificates:

• Test of English as a Foreign Language (TOEFL) — at least 87 points in Internet-Based Test (iBT)
• Test of English as a Foreign Language (TOEFL) — at least 180 points in Computer-Based Test (CBT), supplemented by at least 50 points from Test of Spoken English (TSE)
• Test of English as a Foreign Language (TOEFL) — at least 510 points in Paper-Based Test (PBT) supplemented by at least 3,5 points from Test of Written English (TWE) and supplemented by at least 50 points from Test of Spoken English (TSE)
• Test of English for International Communication (TOEIC) — supplemented by at least 700 points
• European Consortium for the Certificate of Attainment in Modern Languages (ECL)

City & Guilds, City & Guilds Pitman Qualifications, Pitman Qualifications Institute:

• English for Speakers of Other Languages (ESOL) — First Class Pass at Intermediate Level, Higher Intermediate Level, Advanced Level;
• International English for Speakers of Other Languages (IESOL) — „Communicator” level,  „Expert” level, „Mastery” level
• City & Guilds Level 1 Certificate in ESOL International (reading, writing and listening) Communicator (B2) 500/1765/2
• City & Guilds Level 2 Certificate in ESOL International (reading, writing and listening) Expert (C1) 500/1766/4
• City & Guilds Level 3 Certificate in ESOL International (reading, writing and listening) Mastery (C2) 500/1767/6
• Spoken English Test (SET) for Business — Stage B poziom „Communicator”, Stage C „Expert” level, Stage C „Mastery” level
• English for Business Communications (EBC) — Level 2, Level 3; English for Office Skills (EOS) — Level 2

Edexcel, Pearson Language Tests, Pearson Language Assessments:

• London Tests of English, Level 3 (Edexcel Level 1 Certificate in ESOL International)
• London Tests of English, Level 4 (Edexcel Level 2 Certificate in ESOL International)
• London Tests of English, Level 5 (Edexcel Level 3 Certificate in ESOL International)

Education Development International (EDI), London Chamber of Commerce and Industry Examinations Board:

• London Chamber of Commerce and Industry Examinations (LCCI) — English for Business Level 2, English for Business Level 3, English for Business Level 4
• London Chamber of Commerce and Industry Examinations (LCCI) — Foundation Certificate for Teachers of Business English (FTBE)
• London Chamber of Commerce and Industry Examinations (LCCI) — English for Tourism Level 2 — „Pass with Credit” level,poziom „Pass with Distinction”

University of Cambridge ESOL Examinations, British Council, IDP IELTS Australia in particular Certificates:

• International English Language Testing System IELTS — at least 6 points.

Certificates telc GmbH, WBT Weiterbildungs-Testsysteme GmbH:

• B2 Certificate in English — advantage
• B2 Certificate in English for Business Purposes — advantage
• Certificate in English for Technical Purposes (B)