Trial Balance Explained: A Worked Example and Errors It Cannot Catch

A trial balance lists the balances in the ledger, your full set of accounting records, at a chosen date. It usually has debit and credit columns, the two sides of an accounting entry. Double-entry bookkeeping requires their totals to match. Matching totals do not prove that the books are complete, that amounts are in the right accounts or that a tax return is ready.

This guide builds an original, simplified Canadian-dollar example and then deliberately considers errors that the total cannot detect. Use it to understand a report from your accounting system, not to bypass source documents, reconciliations or professional review. The illustration excludes sales taxes and period-end adjustments.

1. Know which report you are reading

An unadjusted trial balance shows balances before the period-end adjustments being reviewed. These adjustments put amounts in the right accounts and periods. An adjusted trial balance includes the approved adjustments. A post-closing trial balance comes after entries that close out the period’s income and expense accounts. The available reports and their layout depend on your system and process.

Confirm the legal entity, currency, cutoff date and report version. A monthly movement report is not necessarily a closing-balance report. Comparing one to the other can create an apparent discrepancy that is really a filter mismatch. Keep the selected parameters with the report you review.

Debit does not mean “bad” and credit does not mean “good.” They are sides of the accounting system. An account's normal balance helps interpretation, but an unusual balance is something to investigate rather than automatically reverse.

2. Read an original balanced example

The fictional business below has eight closing account balances. Each amount appears in the debit or credit column according to its net balance. The example is deliberately small enough to total by hand; a real chart of accounts will normally contain more detail.

Illustrative trial balance — CAD at one closing date

Account	Debit	Credit
Cash	$4,800	—
Accounts receivable	$1,600	—
Equipment	$2,400	—
Operating expenses	$1,200	—
Accounts payable	—	$1,800
Loan payable	—	$2,200
Owner capital	—	$4,000
Revenue	—	$2,000
Total	$10,000	$10,000

Cash, receivables and equipment total $8,800. Liabilities total $4,000. Capital of $4,000 plus the illustrated $800 profit leaves $4,800 of equity. That relationship is consistent, but it still does not verify each asset, liability or expense.

3. Investigate unequal totals methodically

If the columns differ, first confirm that the export includes every intended account and that the spreadsheet totals cover every row. A filter, a text-formatted number, a missing negative sign or a clipped print range can cause an export problem even when the underlying system balances.

Then compare the report with the ledger and recent imports. Look for an entry with only one side included, a balance placed in the wrong column or an amount entered incorrectly. A difference divisible by nine can suggest transposed digits, but it is a clue, not proof of the cause.

• Record the exact difference and the earliest report where it appears.
• Check opening balances before changing current-period entries.
• Trace suspicious amounts to original transactions and evidence.
• Correct the supported error through an authorized process.

Do not add an unexplained entry just to make the totals match. A suspense or clearing account holds amounts temporarily while they are resolved. If you have a valid reason to use one, name someone responsible, record the reason and resolve the item. Moving an amount there does not finish the review.

4. Look for errors that still balance

Suppose a $400 loan-principal repayment is debited to utilities instead of reducing the loan payable, with cash correctly credited. The entry has equal debits and credits. Yet expenses are overstated, profit is understated and the loan remains too high. Equal trial-balance columns do not detect this classification error.

Now imagine an earned $650 customer invoice is omitted entirely. Both the receivable debit and revenue credit are missing. The books can still balance while both assets and income are incomplete. Duplicate balanced entries and wrong-period entries can also survive the arithmetic check.

These examples explain why “the trial balance balances” is not a sufficient review conclusion. A posting can be internally symmetrical and still describe the wrong event, account, customer, entity or period.

5. Connect balances to independent evidence

Compare cash with bank statements and completed bank reconciliations. Check receivables (money customers owe) and payables (money owed to suppliers) against their detailed lists. Check loans against lender records and unusual expenses against supporting documents. Look for missing invoices, expenses incurred but not yet billed, payments made in advance and other adjustments needed for the period.

Use comparative review carefully. A large change from last month may have a valid reason; an unchanged balance may conceal an omitted entry. Ask for the explanation and evidence, not just a percentage threshold. Review unusual signs and dormant accounts that suddenly move.

Record the adjustment reference and approval, then obtain the updated trial balance. Retain the distinction between the report first received and the approved adjusted version so the next reviewer can follow what changed.

6. Make the review reproducible

A useful handover contains the entity, reporting date, report version, reconciled schedules, outstanding questions and reviewer decisions. Keep unresolved issues visible rather than renaming the file “final” to imply a conclusion that has not been reached.

The accounting system produces the trial balance and records corrections. Bookwits can coordinate review tasks and supporting documents, but it does not replace a ledger or independently certify a report. A good process combines arithmetic agreement, substantiated balances and a clear audit trail.