The Spanish Ministry of Foreign Affairs says four categories of foreigners may qualify for citizenship through the option route, a legal mechanism for declaring intent to become Spanish nationals.

The first group includes people who are or were under the parental authority of a Spanish citizen; they must submit their declaration within two years of turning 18 or becoming legally emancipated.

The second category covers individuals born in Spain to a Spanish parent; there is no time restriction for filing the option declaration.

The third group consists of adults who later have their parentage or place of birth legally confirmed as Spanish; they have two years from the date of that legal establishment to apply.

The fourth category applies to people adopted by Spanish citizens after the age of 18; the two‑year deadline starts from the date the adoption is formally completed.

Applicants residing in Spain must file the declaration in person at their local Civil Registry, while those living abroad must begin the process through the Spanish consular office responsible for their location.

The option pathway is distinct from other naturalisation routes that rely on long‑term residence, targeting only those with specific legal or familial ties to Spain.