A trial balance is a bookkeeping worksheet. In this worksheet, the balances of all ledgers are compiled into equal debit and credit account column totals. A trial balance is prepared by companies periodically, usually at the end of every reporting period. The general essence of producing a trial balance is to ensure that the entries in a company’s bookkeeping system are mathematically correct. The cost of sales is a very crucial record in a company’s financial statements, but before these financial statements are prepared, one needs to first get the trial balance.