Spain's public language schools — official certificates at a fraction of private prices.
Details
The EOI network is the state system of public language schools, present in every region and open to anyone aged 16 or over. Most schools teach español para extranjeros alongside foreign languages, running A2 up to C2 with an official certificate at the end of each level that is valid nationwide and never expires. This ministry page explains the system; enrolment is regional, so follow it through to your comunidad autónoma. The catch is scarcity — places are allocated by lottery or queue in September, and Spanish-for-foreigners groups fill fastest.