Wikimedia:Inactiviteitsbeleid
Administrator and bureaucrat accounts which have made no edits or administrative actions for at least 12 months may be desysopped. Subject to the extended absence consideration below, this desysopping is not to be considered permanent, or a reflection on the user's use of, or rights to, the admin tools. The admin must be contacted on their user talk page and via e-mail (if possible) one month before the request for desysopping. Desysopping on inactivity grounds should be handled by Outreach bureaucrats. The summary in the user rights log should make it clear that the desysopping is purely procedural.
If necessary, the user's user page should be edited to clarify the status—particularly if any categorization is involved.
Extended absence
If an editor has had at least two years of uninterrupted inactivity (no edit) between the removal of the admin tools and the re-request, regardless of the reason for removal, the editor will need to instead request through the requests for permissions process.
In the case of an administrator desysopped due to inactivity, if, after the one year of inactivity which led to the desysopping due to inactivity, there is a subsequent one year (12 months) of continued inactivity (no edits), then, if the editor returns after that, the editor will no longer be able to merely re-request the admin tools, but instead s/he will need to request adminship through the requests for permissions process. Again, this means there is a total of at least two uninterrupted years of inactivity.