SingaporeAccountingSyllabus dot point

Which errors slip past a trial balance even though it still agrees?

Identify the errors that do not affect the agreement of a trial balance

A simple answer to the N(A)-Level Principles of Accounts outcome on errors. The six errors that leave a trial balance agreeing, what each one is, and a worked check that the totals stay equal.

Generated by Claude Opus 4.89 min answerUpdated 2026-06-06

Reviewed by: AI editorial process; not yet individually human-reviewed

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What this dot point is asking
The answer
Examples in context
Try this

What this dot point is asking

SEAB wants you to identify the errors that leave a trial balance still agreeing. These are the dangerous ones, because the usual check does not catch them. The central insight is that any error which keeps the debit and credit equal, even if both are wrong, will pass the trial balance unnoticed.

The answer

Why some errors are hidden

A trial balance only checks that total debits equal total credits. So any error that affects both sides equally, or neither side, will not disturb the totals. These errors must be found another way, by careful review or because the figures look wrong.

The six errors that do not affect agreement

Error	What happens
Omission	A transaction is left out completely (no debit, no credit)
Commission	An entry is posted to the wrong account of the same type (rent to wages)
Principle	An entry is posted to the wrong type of account (an asset treated as an expense)
Original entry	The wrong figure is used from the source, but the same wrong figure on both sides
Reversal of entries	The debit and credit are swapped (the right accounts, wrong sides)
Compensating errors	Two separate errors cancel each other out

In every case the trial balance still agrees, because the two sides remain equal.

Telling them apart

Omission leaves nothing recorded. Commission records the right amount on the right sides but in a wrong account of the same class. Principle uses the wrong class of account (asset versus expense). Original entry uses the wrong number consistently. Reversal flips debit and credit. Compensating errors happen to offset.

Worked example

A sole trader's trial balance agrees, but four errors are later found. Show that each leaves the totals equal.

Step 1: Error of omission

A credit sale of $\$ 500 $to Lim was never recorded. Both the debit (Lim) and credit (sales) of$ \ $500$ are missing, so neither column changes. The trial balance still agrees, though sales and receivables are understated.

Step 2: Error of commission

Rent of $\$ 200$ was debited to wages instead of rent. Both are expenses (debit balances), so total debits are unchanged. The trial balance agrees, but rent is understated and wages overstated.

Step 3: Error of principle

A computer costing $\$ 1,500$ was debited to purchases (expense) instead of equipment (asset). The debit total is unchanged because both are debit balances. The trial balance agrees, but profit and assets are both wrong.

Step 4: Error of original entry

A sale was entered as $\$ 360 $instead of$ \ $630$ in both the customer's account and sales. The same figure appears on both sides, so the totals still match, even though both figures are wrong.

Examples in context

Example 1. An asset hidden in purchases. A business buys a $\$ 2,000 $freezer for resale-room storage but debits it to purchases. This error of principle understates assets and overstates the cost of goods, lowering profit, yet the trial balance agrees because both entries are debits and credits of$ \ $2\,000$ . Only someone reviewing the accounts would notice the freezer is missing from non-current assets.

Example 2. A reversed receipt. A clerk receives $\$ 300$ from a customer but debits the customer and credits cash, exactly the wrong way round. The right accounts are used, so the totals still match, but cash is understated and the customer's debt appears to grow. This reversal of entries passes the trial balance and would only surface when the customer queries their statement.

Try this

Q1. Name the error when a transaction is left out of the books entirely. [1 mark]

Cue. An error of complete omission.

Q2. Rent paid is debited to the insurance account by mistake. Name the error and say whether the trial balance still agrees. [2 marks]

Cue. An error of commission (wrong account of the same type); the trial balance still agrees because both are debit balances.

Q3. Explain why an error of original entry does not affect the trial balance. [2 marks]

Cue. The same wrong figure is entered on both the debit and credit sides, so the two totals remain equal even though the amount is wrong.

Exam-style practice questions

Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

Original6 marksName the type of error in each case: (a) a sale to Tan was never recorded at all; (b) rent paid was debited to the wages account; (c) the purchase of a van was debited to purchases; (d) a sale was recorded as

\

540

instead of

450

in both accounts.

Show worked answer →

(a) A sale never recorded: error of complete omission.

(b) Rent debited to wages (both expenses, wrong account): error of commission.

(d) Recorded as $\$ 540 $instead of$ \ $450$ in both accounts: error of original entry (the wrong figure was used from the start, but both sides match).

None of these affects the agreement of the trial balance, because in each case the debit and the credit are still equal.

What markers reward: the correct name for each error, and recognising that all of them leave the trial balance in agreement.

Original4 marksExplain, with an example, what an error of principle is and why it does not affect the trial balance.

Show worked answer →

An error of principle is when a transaction is recorded in the wrong type of account, for example treating an asset as an expense. The double entry is still complete, so the debits and credits remain equal.

Example: buying machinery for $\$ 3,000 $is debited to purchases (an expense) instead of machinery (an asset), with bank credited$ \ $3\,000$ . The debit and credit are equal, so the trial balance still agrees, even though profit and the assets are both wrong.

What markers reward: defining the error as recording in the wrong class of account, a correct example such as an asset treated as an expense, and explaining that the totals still agree because the entry is complete on both sides.