The phrase "administratively separate" is correct and usable in written English.
It can be used in contexts where you want to indicate that two or more entities operate independently in terms of administration or management.
Example: "The two departments are administratively separate, allowing them to function without interference from one another."
Alternatives: "administratively independent" or "operationally distinct".
(I except from this list "Comment," which leads off "Talk" but is an administratively separate entity).
It is the westernmost of the Cook Islands but is administratively separate from them.
Niue, the westernmost of the islands, is an administratively separate state.
This territory remained administratively separate from Papua, where the protective paternalist policies of Sir Hubert Murray (lieutenant governor of Papua, 1908 40) did little to encourage colonial investment.
It lies along the Baltic Sea and surrounds Stockholm, the national capital and seat of the län's governor, yet is administratively separate from that city.
In the far south, Sicily remained administratively separate from Ravenna, as did Sardinia, which followed its own path under increasingly independent "judges" in almost total obscurity until the Pisan and Genoese invasions of the 11th and 12th centuries.
Many perpetrators are simply reduced in rank, fined, or administratively separated from the military.
He was "administratively separated" in August, the Montgomery Advertiser reported.
Transgender servicemembers are supposed to be administratively separated from the Army, and cannot receive treatments for gender dysphoria like hormone therapy or sex-reassignment surgery.
Manning was in fact in the process of being administratively separated from the Army because of Worsley's diagnosis of gender identity disorder (a condition now known as gender dysphoria), which Worsley felt could only be effectively treated outside of the Army.
Research was mainly administered by research institutes and administratively separated from patient care and hospitals.
