Legal action can only be conducted by a proficient legal subject. Generally, someone�s legal proficient is measured from his maturity. One�s maturity is determined by age or marital status. There is dissimilarity on definition of proficient in performing legal action related to land registration in several land offices throughout Indonesia, even when there is already existing Circular Letter from Ministry of Internal Affairs of Directorate General of Agrarian of Directorate of Land Registration Number: Dpt.7/539/7/77 dated 13 July 1977 regarding Legal Mature.
This research used juridical normative research method with statute approach and juridical empiric with descriptive analytic approach. Research location was in Sleman District and Samarinda City, with sources in this research were Head of Sleman Land Office, Head of Samarinda Land Office, Practitioners and Academics, Land Deed Registrars (PPAT) in Sleman District as well as Land
Deed Registrars of Samarinda City. The existence of dissimilarity in definition of proficient in conducting legal action related to land registration in Sleman Land Office and Samarinda Land Office was impacted on different policies in the determination of applicant�s age who may register the land. After promulgation of Circulation Letter of Minister of Agrarian and Spatial/BPN Number 4/SE/I/2015 concerning Mature Age Limitation in Land Services, dated 26 January 2015 Samarinda Land Office started to use provision of age at 18 year/have been married before. The promulgation of this circular letter has ended all dissimilarity of views of Sleman Land Office and Samarinda Land Office regarding proficient in performing legal action related to land registration.

Key Words: Legal Proficient, Land Registration