Trial Balance Errors: How to Find and Correct Them (Worked Examples)

A trial balance lists every account’s balance and checks that total debits equal total credits. When it balances, you have confirmed only that the debit and credit AMOUNTS posted are equal — not that the entries were correct. Whole categories of errors leave the trial balance perfectly balanced: omitting an entire transaction, posting to the wrong account of the same type, recording the wrong amount in BOTH the debit and credit, reversing the debit and credit, and compensating errors that happen to cancel out. The errors a trial balance DOES catch are the ones that break the debit-equals-credit equality: posting only one side, posting different amounts to the two sides, and arithmetic mistakes in the columns. Knowing which bucket an error falls into tells you whether the trial balance can help you find it at all.

Error of omission: an entire transaction is never recorded — both sides are missing, so the trial balance still balances. Error of commission: the right amount is posted to the wrong account of the SAME type (e.g., a payment to Vendor A recorded against Vendor B) — debits still equal credits. Error of principle: an item is posted to the wrong TYPE of account (recording a capital expenditure as a repair expense) — totals balance but the financial statements are wrong. Error of original entry: the wrong amount is recorded in the journal, so both the debit and credit carry the same wrong figure. Reversal of entry: the debit and credit are swapped — still equal. Compensating errors: two independent mistakes that happen to offset. Catching these requires controls beyond the trial balance — bank reconciliations, subsidiary-ledger reconciliations, analytical review, and audits.

When a trial balance is OUT of balance, the size of the difference often reveals the error type. If the difference is evenly divisible by 9, suspect a transposition or a slide. A TRANSPOSITION swaps digits — posting $540 as $450, a difference of $90, which is divisible by 9. A SLIDE misplaces the decimal point — posting $250 as $25.00 (a difference of $225) or $2,500 (a difference of $2,250), both divisible by 9. The math behind it: swapping two adjacent digits changes the number by 9 times the difference between those digits, and shifting a decimal changes it by a multiple of 9 as well. So when you see an out-of-balance amount like $90, $270, or $1,800, divide by 9 first — it points you straight at a transposition or slide rather than a random hunt through the ledger.

If the out-of-balance difference is evenly divisible by 2, suspect that an amount was posted to the WRONG SIDE — debited when it should have been credited or vice versa. Posting a $300 credit as a $300 debit overstates debits by $300 and understates credits by $300, throwing the trial balance off by $600 — exactly twice the item. So divide the difference by 2 and look for an entry of that amount posted on the wrong side. A difference that equals a single round number you recognize often means a one-sided posting (only the debit or only the credit was entered). Working the two shortcuts in order — divide by 9, then divide by 2, then scan for the raw difference — resolves the large majority of out-of-balance trial balances quickly.

A trial balance shows total debits $84,600 and total credits $84,690 — out of balance by $90. First test: 90 ÷ 9 = 10, evenly divisible, so suspect a transposition. Scanning the credit side, you find Accounts Payable recorded as $4,560 when the supporting documents show $4,650 — the 5 and 6 were swapped, a $90 understatement of credits. Because this is purely a posting error in one account, the cleanest fix is to correct that account’s balance directly: increase Accounts Payable by $90. If the error were embedded in a posted journal entry, you would record a correcting entry — for instance, if Equipment was debited but Repairs Expense should have been, you would debit Repairs Expense and credit Equipment to reclassify. The rule: identify what was recorded, what should have been recorded, and write the entry that moves from one to the other.

Snap a photo of an out-of-balance trial balance and AccountingIQ computes the difference, runs the divide-by-9 and divide-by-2 tests, suggests the likely error type, and — once the mistake is identified — drafts the correcting entry. For errors a trial balance cannot catch, it flags the reconciliations that would surface them. This content is for educational purposes only and does not constitute professional accounting advice.