In a trial balance, incomes are credited while liabilities are credited. This is because incomes increase the owner's equity in the business and so are credited, while liabilities are obligations of the business to pay a debt or settle an obligation in the future, hence they are credited. In the double entry system of bookkeeping, every transaction has two aspects - a debit and a credit - so in a trial balance, the total debits should equal the total credits, which ensures that all transactions have been correctly recorded.