Limitations of the Trial Balance

A Trial Balance agreeing is reassuring, but it is not proof that the books are entirely free of errors — it only proves that debits and credits are numerically equal in total. Several kinds of errors can exist even when the Trial Balance agrees perfectly:

• Error of Omission — a transaction is left out of the books entirely (not journalised at all). Since neither a debit nor a credit was recorded, the omission cannot unbalance the Trial Balance.
• Error of Commission — an entry is posted to the wrong account, but on the correct side and for the correct amount, e.g. a payment to Ramesh posted to Ramu's account instead — both accounts belong to the same category, so the Trial Balance still agrees.
• Error of Principle — a transaction is recorded by violating a basic accounting principle, e.g. capital expenditure (buying a machine) wrongly debited to an expense account (Repairs A/c) instead of an asset account — the amount and side are technically 'correct' in the sense that debits still equal credits overall, but the classification is wrong.
• Compensating Errors — two or more independent errors happen to cancel each other out in total, e.g. Account A is overcast (over-totalled) by ₹500 and, quite separately, Account B is undercast (under-totalled) by ₹500 — the Trial Balance still agrees even though two real errors exist. …