# Bank Reconciliation Errors: Types and Where They Hide

- Author: PreciseBankFlow (https://www.precisebankflow.com)
- Published: 2026-06-25
- Updated: 2026-06-25
- Category: Finding reconciliation errors
- Canonical: https://www.precisebankflow.com/blog/bank-reconciliation-errors

> The bank reconciliation errors that cause most differences: omissions, duplicates, transpositions, wrong signs and wrong periods, and the test for each.
Most bank reconciliation errors fall into five types: omissions, duplicates, transpositions or slides, wrong signs and wrong periods. Each leaves a difference with its own shape. An omission equals one line, a duplicate equals one line, a swap divides by nine, a wrong sign doubles the amount, and a period error clears next month.

## Which bank reconciliation errors cause most differences?

The bank reconciliation errors that cause most differences are five book-keeping mistakes and one outside cause. The five are omitted entries, duplicate entries, keying errors in amounts, entries with the wrong sign, and entries in the wrong period. The outside cause is an error, or something worse, on the bank statement itself.

The shape of the difference narrows the search before you look at a single line. The table below maps each error type to that shape and to the test that finds it. The example amounts are invented.

| Error type | Example | Shape of the difference | Test |
| --- | --- | --- | --- |
| Omission | 85.00 bank fee never booked | Equals one statement or ledger line | Search for a line of exactly that amount |
| Duplicate | 2,750.00 deposit entered twice | Equals one ledger line | Sort ledger by amount, look for pairs |
| Transposition | 4,562.00 keyed as 4,526.00 | Divides evenly by 9 | Divide by 9, look for digits that differ by the result |
| Slide | 1,250.00 keyed as 125.00 | Nine or ninety-nine times the smaller amount | Divide by 9 and 99, look for the result |
| Wrong sign | 400.00 refund booked as a payment | Twice the amount | Halve the difference, search for that amount |
| Wrong period | 31 March deposit dated 1 April | Clears the next month | Compare lines dated near month-end |

### Errors that offset or combine

Combinations are common. Two errors of different types can offset each other, or add up to a figure with no clear shape. An omitted 85.00 fee plus a transposition worth 36.00 leaves 121.00, which matches no line and does not divide by nine. Clear the errors you can identify first, then test what remains. When the difference is small but the month was busy, be suspicious of a near-zero net; two large errors in opposite directions can leave only a few cents between them. A reconciliation that agrees exactly can still hold offsetting errors, which is why the reviewer checks the matched lines and not only the final figures. For the order of work when you start with a difference and no idea of its cause, see [how to find a reconciliation difference](/blog/find-a-reconciliation-difference).

## Omitted bank entries: the line nobody booked

An omitted entry is a transaction that appears on one side and not the other. The bank posted a fee, interest or a returned item that never reached the ledger, or the ledger holds a payment that never happened at the bank. The difference equals that one line, which makes omissions the easiest error to find once you suspect one.

The bank side causes most omissions in the ledger. Service charges, interest earned, returned deposits, automatic loan payments and card processor deductions are all set off by the bank or a third party, without a document landing on anyone's desk. They show up only on the statement.

Omissions from the bank side are rarer and usually timing. A check written on the last day of the month is in the ledger and not yet at the bank. That is an outstanding check, not an error. It becomes an error only if it never clears because it was never sent.

To find an omission, take the exact difference and search both the statement and the ledger for a line of that amount. If none matches, try the difference against small groups of lines, such as all fees in the month.

## Duplicate entries on a bank reconciliation

A duplicate entry is one transaction recorded twice. It leaves the book balance wrong by the amount of the doubled line, and it usually shows as an item that never clears: a deposit in transit that never arrives or an outstanding check that never cashes. Sorting the ledger by amount puts the pair side by side.

Duplicates come from having two routes into the ledger. A bank feed brings in a deposit while a clerk records the same receipt by hand. A bill is paid by check and again by transfer. A spreadsheet import runs twice. The pair has the same amount and close dates, and often slightly different descriptions, which is why it is missed.

Not every repeat is a duplicate. A monthly rent payment repeats on purpose, and a customer can genuinely pay twice. The test is whether the bank shows the transaction once or twice. One bank line behind two ledger lines is a duplicate.

## Transposed and slid amounts in the cash ledger

Transpositions and slides are keying errors in the amount itself. A transposition swaps two digits, so 4,562.00 becomes 4,526.00. A slide moves the decimal, so 1,250.00 becomes 125.00. Both leave a difference that divides evenly by nine, which is the test that exposes them.

For a transposition, divide the difference by nine. The result tells you how far apart the swapped digits are. A difference of 36.00 divides to 4, so look for an amount whose tens and units digits differ by four, such as 26 or 62.

For a slide, divide by nine and by ninety-nine. A one-place slide leaves nine times the smaller amount and a two-place slide ninety-nine times, and [slide error accounting](/blog/slide-error-accounting) shows how to tell a slide from a swap. The quotient arithmetic for swaps is set out in [what a reconciliation difference divisible by 9 means](/blog/reconciliation-difference-divisible-by-9).

The divide-by-nine test is only a pointer. About one difference in nine divides evenly by chance. Confirm each candidate against the source document before correcting it.

## Wrong-sign errors and the doubled reconciliation gap

A wrong-sign error records money moving the wrong way: a deposit entered as a payment, or a refund entered as a charge. The book balance then moves by twice the amount, once to undo the correct effect and once for the incorrect one. Halve the difference and search for that amount.

Example: a supplier refund of 400.00 is received, but the bookkeeper enters it as a 400.00 payment. The books should have gone up by 400.00 and instead went down by 400.00. The reconciliation is out by 800.00, bank side higher. Halving 800.00 gives 400.00, and the search turns up the refund.

Wrong signs are common with refunds, reversals and transfers, because the same counterparty appears on both sides of the business. They also appear in imports where the debit and credit columns are mapped the wrong way round, which flips every line and makes the difference twice the net activity for the period.

A related trap is the bank reversal: an original transaction and its reversal both on the statement, with only one of them in the ledger. [Handling a reversed bank transaction](/blog/reversed-bank-transaction) explains how to match the pair.

## Wrong-period entries at the bank statement cut-off

A wrong-period error records a transaction in a different month from the one in which it belongs. It sits near month-end: a deposit dated 1 April that the bank posted on 31 March, or a check dated in the next month by mistake. The difference appears in one month and disappears in the next.

These errors are tricky because they correct themselves. A deposit booked a day late shows in March as an unrecorded bank credit on the book side. In April the ledger entry catches up and the item drops off without appearing on the April statement. Over the two months, the books are right. Within March, both the reconciliation and the monthly report are wrong.

To find them:

- List every ledger and statement line dated within three days of month-end on either side.
- Compare the ledger date with the bank posting date for each.
- Check postdated checks, which some businesses enter on the date written rather than the date on the check.

Period errors matter most at year end, when a deposit or payment in the wrong year moves income or expenses between tax years.

## Can the bank make reconciliation errors too?

Banks make reconciliation errors too, though rarely. A teller can key a deposit wrong, a check can clear for a different figure, or a transaction can post to the wrong account. These are bank errors. They are corrected by the bank, and the reconciliation carries them as bank-side items until the correction appears.

Signs of a bank error:

- The source document, such as a deposit slip or check image, agrees with the ledger and not with the statement.
- A transaction appears that belongs to another customer.
- A fee does not match the account's fee schedule.

Keep the evidence and contact the bank in writing. Do not change the books to match a figure you can show is wrong.

A different problem is a statement that is not genuine. A statement that has been edited, for example to hide a withdrawal or inflate a balance, will never reconcile cleanly against real activity, and the difference can look like an ordinary error. If the numbers fail in ways no book error explains, compare the copy you were given with one downloaded directly from the bank. [Spotting an edited PDF bank statement](/blog/edited-pdf-bank-statement) covers the signs.

[PreciseBankFlow](/) checks that every statement foots before matching it, so a statement whose lines do not add up to its own closing balance is flagged before any book-side search begins.