In general, Spanish Social Security covers all persons at least 16 years of age who work in Spain or who work outside the country but maintain their residence in Spain. A worker's occupation determines whether the worker is covered under the general system or one of the special systems mentioned in GN 01721.010.

Covered employees and their employers, as well as covered self-employed persons, are subject to compulsory contributions which are based on a percentage of the worker's earnings. Contributions are subject to an annual earnings ceiling that varies depending on the worker's occupational class.

Spain permits people who are not subject to compulsory contributions and who meet certain qualifying conditions to make voluntary contributions to build future benefit rights.

GN 01721.130, Voluntary Contributions to the Spanish System