The term is a modern financial compound, built from native English word-forming elements. The noun "tax," with its Latin roots concerning assessment, combines with the verb "shelter," which originates from the Old English military term for a shield-wall, evoking a powerful image of protection. The adjectival suffix "-ed" is then appended, indicating the condition of having been shielded. Thus, the literal logic of "having been shielded from tax" perfectly captures the modern financial meaning, where certain investments or accounts are legally protected from immediate taxation.

Structure: tax (noun) + shelter (verb) + ed (adjective suffix) - tax: From Latin taxare ("to appraise, handle, censure"), via Old French. In this compound, it functions as a noun meaning a compulsory contribution to state revenue. - shelter: From Middle English sheltron ("phalanx, body of troops"), via Old English scieldtruma (scield "shield" + truma "troop"). Its modern verb sense "to protect" developed in the 16th century. Here, it functions as a verb root meaning "to protect or shield". - ed: A native English suffix forming adjectives from verbs, indicating the state or condition resulting from the action.