All registered causes have a unique identification number issued by the governing country where they operate. Sometimes the number is also referred to as a "government ID number".
You can find your registration number in your government registration confirmation documents. See below for some examples of registration numbers by country.
Australia: 11-digit ABN (Australian Business Number).
Brazil: 14-digit CNPJ (Cadastro Nacional da Pessoa Jurídica).
Canada: Business number issued by the CRA (Canada Revenue Agency). Usually, it will look something like 123456789RR0001.
Ireland: 3 to 6-digit CHY reference number.
India: Permanent Account Number (PAN). Format: 356-XXXXXXXXXX - usually starts with “AAA”, and is alphanumeric.
United Kingdom: 4 to 7-digit registration number.
United States: 9-digit identification number called an EIN (Employer Identification Number) issued by the IRS. Some U.S. charities may be chapters of larger parent organizations and may use that parent's charity status and EIN.
Please check local government websites for identification number requirements for any countries not listed here.