As a general rule, unless a specific regulation exempts it from this requirement, any foreign public document must be legalized or apostilled to be valid and recognized in Spain; this process verifies the authenticity of the signature and the official capacity of the authority signing the document.

There are two main ways to legalize the academic documentation required for application in official master's degree programs:

1. Hague Apostille (Fast-track method)
   
   This is the simplified legalization procedure applicable between member states of the Convention.
   
   Step 1: Recognition of signatures at the Ministry of Education in the country of origin.
   Step 2: Application for the Hague Apostille from the competent authority (usually the Ministry of Justice or Ministry of Foreign Affairs of the country of origin).
    
2. Diplomatic or Consular Channel
   
   This method is used if your country of origin is not a member of the Hague Convention; it is a longer process.
   
   Step 1: Legalization at the Ministry of Education in the country of origin.
   Step 2: Legalization at the Ministry of Foreign Affairs in the country of origin.
   Step 3: Legalization at the Spanish Consulate or Embassy in the country of origin (in some cases, the documentation must be translated).

Legalization does not certify the content of the document. Legalization or the apostille does not expire; however, if the document itself has a limited validity period, the legalization or apostille will be subject to that same limit.