Key Takeaways
- A trial balance proves arithmetic equality of debits and credits but does not detect errors that preserve that equality (such as posting to the wrong account).
- Auditors typically receive two versions: the pre-adjustments TB at the start of fieldwork and the post-adjustments TB after all audit entries are processed.
- A mismatch between total debits and total credits always indicates a posting error or a one-sided entry.
- After all adjustments, the closing TB ties directly to the face of the FS. Any unexplained difference between the two signals an incomplete mapping.
What is a trial balance?
Every audit file starts the same way: request the trial balance and start ticking and bashing. It is the most routine document on the engagement, and it is also the one that causes the most rework when the client sends a version that does not agree to the financial statements the team has already started testing against.
A trial balance is an output of the general ledger. The entity's accounting system extracts every account with a non-zero balance at the reporting date and presents the balances in two columns: debits and credits. If totals do not match, a mechanical error exists somewhere in the ledger, and the entity must locate it before proceeding.
On an audit engagement, the TB is the starting point for substantive work. ISA 500 .A2 describes the auditor's obligation to obtain audit evidence that is sufficient and appropriate. In practice, the engagement team maps the client's TB to the financial statement line items (often called a "lead schedule" or "grouping schedule") and then tests the resulting balances. ISA 330.20 requires the auditor to perform substantive procedures for each material class of transactions and each material account balance. That process begins with the TB.
Two versions matter. The opening TB (before adjusting entries) reflects the entity's own bookkeeping. After audit adjustments and reclassifications, the adjusted TB reflects the figures that will appear in the signed financial statements. Nobody enjoys reconciling the two when the client has posted entries after sending the "final" version, but skipping that step is how files get flagged at review. Auditors document each adjustment as a journal entry with a cross-reference to the working paper that supports it.
For group engagements, the group engagement team receives component TBs from each subsidiary. ISA 600.25 expects the group team to evaluate whether each component TB has been properly translated into the group's presentation currency and whether intercompany balances eliminate to zero. We've seen SALY grouping schedules carried forward year after year without anyone checking whether the client added new accounts. A TB that does not balance after consolidation adjustments is a red flag that an elimination entry is missing or misstated.
Related terms
Related reading
Frequently asked questions
What errors does a trial balance not detect?
A balanced trial balance proves only that total debits equal total credits. It cannot detect: transactions posted to the wrong account (classification errors), transactions omitted entirely from both sides (errors of omission), compensating errors that cancel each other out, or transactions recorded at the wrong amount on both sides (errors of original entry). This is why auditors never rely on a balanced trial balance alone and perform substantive testing under ISA 330.
What is the difference between an unadjusted and adjusted trial balance?
The unadjusted trial balance shows general ledger balances before period-end adjustments. The adjusted trial balance includes all adjusting entries — accruals, deferrals, depreciation, impairment, and reclassifications. The adjusted trial balance is the starting point for preparing the financial statements under IAS 1 and the primary document the external auditor reconciles to the financial statements during the audit.
Why do auditors request the trial balance early in the engagement?
The trial balance is the auditor's primary link between the entity's accounting records and the financial statements. ISA 500.A5 recognises the accounting records (including the trial balance) as a source of audit evidence. Receiving it early allows the auditor to perform analytical procedures under ISA 520, identify unusual balances or movements for further testing, and plan the nature and extent of substantive procedures before fieldwork begins.