The trial balance and what it can't tell you¶
You just spent a month posting transactions to dozens of T-accounts. Before you trust those ending balances enough to build an income statement or a balance sheet, you need one gut check: do the debits and credits still line up? A trial balance is that gut check, and it takes about two minutes to build once you know the trick. It is also, on its own, a much weaker check than most students assume.
Every account's ending balance, in one place¶
A trial balance lists every account in the ledger, in statement order (assets, then liabilities, then common stock, then retained earnings, then dividends, then revenue, then expenses), with each one's ending balance in a Debit or Credit column. You build it by walking through the ledger (Section 5) one account at a time, reading off the ending balance, and dropping it into whichever column matches that account's normal balance. Nothing gets added, subtracted, or estimated here; it's a transcription step.
Take Harbor Music Lessons at the end of its first month, January. Its ledger shows these ending balances:
| Account | Debit | Credit |
|---|---|---|
| Cash | $6,650 | |
| Accounts Receivable | $2,250 | |
| Prepaid Insurance | $1,050 | |
| Equipment | $3,100 | |
| Salaries Payable | $2,450 | |
| Utilities Payable | $1,400 | |
| Common Stock | $9,900 | |
| Dividends | $950 | |
| Service Revenue | $5,600 | |
| Salaries Expense | $2,850 | |
| Utilities Expense | $1,500 | |
| Advertising Expense | $1,000 | |
| Totals | $19,350 | $19,350 |
Every asset, the Dividends account, and every expense keep their debit balances on the left. Every liability, Common Stock, and Service Revenue keep their credit balances on the right. Add each column and $19,350 meets $19,350. Notice there's no Insurance Expense: this is Harbor's first month, so none of the Prepaid Insurance has been adjusted yet, and no Insurance Expense exists to list. Salaries Expense $2,850 and Utilities Expense $1,500 each cover at least as much as the payable they're tied to, because a payable can only exist for an expense already incurred. Because this list comes straight from the ledger, before anything in Chapter 3 adjusts a single balance, accountants call it the unadjusted trial balance.
What equal totals prove, and what they don't¶
If the two columns match, all that's guaranteed is debits = credits. That's worth having: it catches a huge share of everyday slip-ups, like posting only one side of an entry or copying a number wrong onto a T-account. But matching totals is a much narrower claim than "the books are correct," and it's easy to round it up to more than it says.
Common mistake: assuming a balanced trial balance means the books are right
A trial balance only checks that the total debits recorded so far equal the total credits recorded so far. It can't tell you whether those debits and credits went to the right accounts, or whether an entire transaction is missing. A missed entry, a doubled entry, or the right dollar amount landing in the wrong account can all leave both columns exactly equal while the underlying balances are wrong.
Errors that do and don't break the balance¶
The reason equal totals aren't proof is that some errors hit both columns the same way, while others hit only one.
| Error | Still balances? | If not, off by |
|---|---|---|
| Digits transposed when posting one side of an entry | No | The size of the transposition, always a multiple of 9 |
| A debit amount posted to the credit side of the correct account | No | Twice the amount; credits exceed debits |
| An entire journal entry never posted | Yes | Not applicable |
| The same journal entry posted twice | Yes | Not applicable |
| The debit sent to the wrong account of the same type (Supplies instead of Equipment) | Yes | Not applicable |
| One side of an entry posted twice | No | The amount, on the side that got doubled |
| Only one side of an entry posted, the other left out | No | The amount, on the side that did get posted |
The pattern: an error still balances when it touches nothing (a missing entry), touches both columns by the same amount (a duplicate), or moves an amount around within one column (the right amount, but in the wrong account of the same normal balance). An error breaks the balance when it changes one column without changing the other, or changes the two columns by different amounts. Chapter 3 picks up right where this leaves off: even a perfectly balanced trial balance still needs adjusting entries before it's ready to become financial statements.
Pause and work¶
First, build a trial balance from a jumbled list of ending balances, the same way you'd get one on a homework set.
Next, practice spotting which errors an out-of-balance trial balance would catch. This generator is multiple choice, and there's no partial answer to fade into for a multiple-choice question, so it goes straight from a worked example to two rounds on your own.