'internally-assessed' is a compound of 'internally' and 'assessed'. 'Internally' originates from Latin, specifically the word 'internus', where the root 'inter-' meant 'inside, between' and the adjectival form later took the suffix '-ly' to form the adverb. 'Assessed' originates from Latin, specifically the word 'assessare' (related to 'ad-' + 'sedere'), where 'ad-' meant 'to/toward' and 'sedere' meant 'to sit', used in contexts of sitting beside for judgement.

'internally' came into English via Medieval/Modern Latin and Middle English from Latin 'internus' (through Old French/Medieval Latin influence) and took the adverbial suffix '-ly'; 'assessed' developed from Latin 'assessare' to Old French forms (e.g. 'assesser') and Middle English forms (e.g. 'assessen'/'assess'), eventually becoming the modern English 'assess' and its past participle 'assessed'.

Initially, roots related to 'assess' carried the sense of 'to sit beside (for judgement)', and over time the meaning shifted to 'determine value, evaluate or impose (a tax, grade, etc.)'; combined as 'internally-assessed' it now specifically means 'evaluated within the organization'.