You would need the following documents:

• signed declaration for Charter's acceptance;
• filled inquiery form;
• copy from pay order

Please download documents from here.
The membership fee is as follows:

• Initiation fee - 25 euro (payable once but not excluding the annual fee for the first year)
• Physical person - 25 euro per year
• Non-government organisations, nature parks, local authorities and sole traders - 50 euro per year
• For-profit organisations - 75 euro per year

Bank account of BAAT:
Eurobank Bulgaria
IBAN: BG22BPBI79421042396901
BIC: BPBIBGSF 

Thank you!