Adjustments become necessary at the time of preparing final accounts because the balances shown by the trial balance do not always represent the complete and correct financial position of a business for a particular accounting period. The trial balance mainly contains those transactions that have already been recorded in the books, whereas certain expenses, incomes, assets, and liabilities may relate partly to the current period and partly to another period. Some transactions may also remain completely unrecorded until the final accounts are prepared. Therefore, adjustment entries are passed to ensure that revenues and expenses are recorded in the correct accounting period and that assets and liabilities are shown at their proper values. The main objective of adjustments is to follow the accrual and matching concepts of accounting. According to the accrual concept, income and expenses are recognized when they are earned or incurred, rather than only when cash is received or paid. The matching concept requires that expenses relating to the revenue earned during an accounting period should be charged against that revenue. Adjustments also help in determining the correct amount of profit or loss and presenting a true