Graphic description of Brahman, Īśvara, kūṭastha and jīva. The top one is Parabrahman, which is beyond comprehension. Below Parabrahman is Brahman, who has māyā superimposed on It. Below Brahman is Īśvara, who is limited by māyā. Next to Īśvara are kūṭastha-s, individual souls afflicted with avidyā. Kūṭastha-s also have Brahman and māyā in them. Next to Kūṭastha-s is jīva-s, who have Brahman, māyā and avidyā in them.

Lalitā Sahasranāma 896 explains kūṭastha.

Kūṭ means unintelligible which means ignorance, an influence of māyā.  Ignorance is the outcome of indulging in saṁsāra (worldly affairs) and stha means occupied with or engaged in.  Therefore, kūṭasthā means engaging in ignorance.  This nāma says that She abides in ignorance!

{Further reading on kūṭasthā:  Brahman is reflected in countless facets of māyā or the innumerable individual ajñāna (unintelligible) also known as soul. Ignorance is the casual body of an individual. Under its spell the finite soul gets identified with mind and appears as the ego.  Ego further identifies with sensory organs and becomes an individual being.  The ego is always subjected to change.  Behind this ever changing ego, the changeless Brahman shines as the immutable Self and this is known as kūṭasthā. When the individual soul functions as the experiencer (known as bhokta) and the doer (kartā), the immutable Self (kūṭasthā) stays behind as a witness (sākṣi) for all actions.  The unchangeable Self is not affected by ignorance as it is only a witness and does not partake in both mental and physical actions.  She is called as Kūṭasthā because She is not subjected to change.  Changes occur only if associated with thoughts and actions.  This is also known Kūṭastha caitanya or Kṛṣṇa consciousness or Christ consciousness.}

Kṛṣṇa also refers to Kūṭasthā in Bhagavad Gita (XII.3).  He says “Kūṭastha macalam dhruvam” which means changeless, constant and immovable (the Brahman).