Año Santo Jacobeo (or in galician language Ano Santo Xacobeo) is the holy year of St. James. It takes place the year when the 25th of July (day of St. James) is a Sunday.
This happens with a fixed period of 6-5-6-11 years which implies that there are fourteen Años Santos Jacobeos every century. During the St. James holy year the catholics can get the bula jubilaror jubileo – jubilee indulgence. In order to obtain it they must:
1. After a pilgrimage of at least 100 km, visit the cathedral of Santiago de Compostela where St. James the Great was buried.
2. Pray some prayer (at least the Credo, Our Father and pray for the Pope’s intentions). It is recommended to attend to mass.
3. Receive the Sacraments of Penance (it may be between 15 days before and 15 days after) and Communion.
In summary, the jubilee grace consist of a plenary indulgence in order to forgive the punishment that the sins deserve.
The first Año Jubilar or Jubilee Year was granted by the Pope Calixtus II in 1126. The last Jubilee Years were in 1993, 1999 and 2004. The next ones will be in 2010 and 2021.
The period 6-5-6-11 of the años jacobeos or holy years has its explanation in the frequency of the leap-years and in the fact that the week has 7 days. If there were no leap-years we would have año jacobeo every 7 years. If there is any modification in the sequency of leap-years automatically the cadency of st. james holy years is modified as well. That happened in the Gregorian Reform in the year 1582 and therefore happens in the years that are multiple of 100 but not multiple of 400.