What causes a bank reconciliation to not balance?

In order of likelihood: a transaction was entered twice or not at all, an amount was transposed or mistyped, a bank fee or interest payment was never booked, a deposit in transit or outstanding check wasn't accounted for, or the beginning balance itself was wrong because a prior period's reconciliation was never actually correct.

By Zuny Fester, Head of Operations and Marketing

Reviewed by Zuny Fester

Published September 10, 2026Last reviewed September 10, 2026Editorial policy

Part of the payment reconciliation and cash application guide.

Most common cause	A duplicate or missing transaction entry
Second most common	A transposed or mistyped amount
Easy to miss	Bank fees or interest never booked to the ledger
Where to check first	The difference amount itself — many causes leave a telltale figure

Let the difference amount point you at the cause

Before searching transaction by transaction, look at the size and shape of the difference. A difference divisible evenly by 9 is the classic signature of a transposed number (swapping two digits, like 54 for 45, always produces a difference divisible by 9). A difference that exactly matches a single transaction amount usually means that transaction was either duplicated or omitted entirely. A small, oddly specific difference (like $12.50 or $35.00) is often an unbooked bank fee or interest amount.

The five causes, in order of how often each one is the answer

Duplicate or missing entry — a transaction was recorded twice in the books, or a bank transaction (a card payment, an ACH debit) was never entered at all.
Transposed or mistyped amount — a manually entered number doesn't match what actually cleared the bank.
Unbooked bank fees or interest — monthly service charges, wire fees, or interest earned that the bank deducts or adds automatically, without a corresponding manual entry in the books.
Timing items not accounted for — a deposit in transit (recorded in the books, not yet on the bank statement) or an outstanding check (written and recorded, not yet cleared) that the reconciliation formula didn't include.
A wrong beginning balance — if the prior period's reconciliation wasn't actually correct when it was marked complete, every subsequent period inherits that error until someone finds it.

How to isolate it methodically

Reconcile the current period in isolation first, checking that every transaction on the bank statement has a matching book entry and vice versa, before assuming the problem started in the current period at all. If the current period's transactions all tie individually but the totals still don't balance, the error is almost certainly in the beginning balance, which means it originated in a prior period that was closed without actually being correct.

Next step

Map the finance workflow with the most exposure and prove the automation path.

Bring the invoice, contract, payment reconciliation, or customer finance workflow you have to defend at audit. Loopfour can map the trigger, controls, integrations, and approval loop.

Book a workflow review

Checklist

Bank reconciliation difference triage checklist

Is the difference evenly divisible by 9? Look for a transposed digit.
Does the difference exactly match one transaction's amount? Check for a duplicate or omission.
Is the difference a small, round-ish number? Check for unbooked bank fees or interest.
Are all deposits in transit and outstanding checks from last period accounted for this period?
If the current period ties transaction by transaction but the total still doesn't, check the prior period's ending balance.

Frequently Asked Questions

Not always, but it's a strong signal worth checking first — a transposed two-digit swap always produces a difference divisible by 9, so it narrows the search considerably even though other causes can occasionally produce the same divisibility by coincidence.

That points squarely at last period's reconciliation being wrong when it was marked complete — you'll need to reopen and correct that period, not just adjust the current one.

No — a plug entry hides the actual error rather than fixing it, and it will resurface, usually at a worse time, such as during an audit or a subsequent period's reconciliation.

Sources

Topic

Payment Reconciliation & Cash Application

Payment reconciliation is the process of proving that every dollar that hit your bank account is accounted for somewhere in your books — matched to a deposit, a payout, an invoice, or an explained var…

Integration

Why don't my Stripe payouts tie to the NetSuite bank deposit?

A Stripe payout rarely equals one NetSuite deposit line: Stripe nets many charges, fees, and refunds into one transfer settled days later. Check, in order: the payout isn't unbundled into individual charges, the deposit date doesn't match the transaction date, fees are netted not booked separately, a partial capture created a variance, or the payout is still in Undeposited Funds.

Diagnostic

How do I shorten the close when AP reconciliation is the bottleneck?

Move AP-to-bank reconciliation to a rolling, weekly cadence instead of a single close-week event, so most of the matching work is already done by the time the period ends. Most AP bottlenecks at close aren't caused by close-week work itself — they're a backlog of sync gaps and unmatched payments that accumulated all month and only get discovered when someone finally looks.