Betterments definition. Analyzing the definition of key terms often provides more insight about concepts. Betterments can be defined as – Expenditures to make a plant asset more efficient or productive; also called improvements. As opposed to normal repairs, betterments will be capitalized as an asset when incurred because betterments generally extend the useful life of assets. Therefore, we need to allocate the cost, expensing the cost, in the period the betterment was used rather than when the period that betterment was purchased. The idea of capitalizing betterments is in accordance with the accrual matching principle.