'rent-paying' is a modern English compound formed by combining the noun 'rent' and the present participle 'paying' of the verb 'pay'.

'rent' comes from Middle English 'rente' (Old French rente) meaning a regular payment; 'pay' comes from Old French 'paier' (from Latin roots related to settling or satisfying a debt). The compound pattern noun + present participle (e.g., 'money-making', 'time-saving') is a productive modern English formation that produced 'rent-paying'.

Initially both components kept their original literal senses ('rent' = payment for use; 'paying' = giving money). Over time the compound came to be used idiomatically as an adjective describing tenants, tenancies, or properties that involve payment of rent or produce rent income.