Why Your Bank Reconciliation Doesn't Match (And How to Find the Error)

Your books say your checking account has one balance. Your bank statement says another. Neither number is necessarily wrong — but until you know why they don't match, you can't trust either one. Here's the order to check things in, so you're not re-reading every transaction from the month one at a time.

Bank reconciliation is the process of comparing your own records (your “book balance”) to what the bank says (your “bank balance”) and accounting for every difference until both numbers agree exactly. It's not optional bookkeeping housekeeping — it's how you catch a bounced payment, a duplicate charge, a bank error, or a transaction you forgot to record, before it quietly throws off your financial statements or your tax return.

First: A Mismatch Is Normal, Not a Sign Something's Broken

Almost every reconciliation is off on the first pass. That's expected — a bank account can have dozens of transactions moving at different speeds. The mismatch isn't proof of a mistake in your business; it's proof the reconciliation is doing its job by surfacing timing differences before they turn into real errors.

The Five Things That Almost Always Cause a Mismatch

Work through these in order — most mismatches are explained by the first two.

1. Outstanding Checks (or Cheques)

You wrote a check and recorded it in your books, but the person you paid hasn't cashed it yet, so the bank hasn't deducted it. Your book balance is already lower than the bank's; it'll catch up once the check clears.

2. Deposits in Transit

You received a payment and recorded it, but the bank hasn't processed it yet — common with a night deposit, a check that takes a day or two to clear, or a transfer initiated late in the day. Your book balance is already higher than the bank's for the same reason, in reverse.

3. Bank Fees and Interest You Haven't Recorded Yet

Monthly maintenance fees, per-check fees, and interest earned show up on the bank statement automatically but don't land in your books until you add them. These are usually small, but they're also the easiest to forget entirely.

4. An NSF (Non-Sufficient Funds) Item

If a customer's check bounced — the banking term is NSF, meaning the payer's account didn't have enough money to cover it — the bank reverses that deposit and often charges a fee. If you already recorded the original payment as received, you now need to back it out.

5. A Recording Error, on Either Side

You entered the wrong amount, entered a transaction twice, or the bank made an error on its end (rare, but it happens). This is the slowest one to find, which is exactly why it's last — rule out the timing differences above first.

How to Actually Run the Check

1. Start With the Easy Math

Take the bank's ending balance, add any deposits in transit, subtract any outstanding checks. That should equal your adjusted bank balance.

2. Adjust Your Book Balance

Take your book balance and add anything the bank knew about before you did — interest earned, a payment collected on your behalf — then subtract anything you hadn't recorded yet, like fees or an NSF reversal.

3. Compare the Two Adjusted Numbers

The two adjusted numbers should now match exactly. If they don't, the remaining gap is almost always a recording error: a transposed digit, a transaction entered twice, or one posted to the wrong account or for the wrong amount.

4. Record the Adjustments

Once they match, record the adjustments — the fees, interest, and any NSF reversal — as actual entries in your books. The reconciliation itself doesn't fix your records; it tells you what still needs to be entered.

What Reconciliation Can't Catch

A reconciliation only proves your book balance and your bank balance agree — it doesn't prove every transaction was recorded to the right account. If you paid a supplier and accidentally categorized it as an owner draw instead of an expense, your cash balance still reconciles perfectly, because the dollar amount left your account correctly either way. That kind of error shows up later, on your financial statements, not here. (If you've already run into a version of this on your trial balance instead of your bank account, the same logic applies — see Why Doesn't My Trial Balance Balance?)

Why This Matters Beyond Just “the Numbers Agree”

Reconciling regularly — monthly, at minimum, for every account you use for the business — is also what keeps your records defensible if a tax authority ever asks questions. In Canada, the CRA requires businesses to keep records, including bank statements and reconciliations, for six years from the end of the tax year they relate to. In the US, the IRS's general rule is three years from when you filed (or two years from when you paid the tax, whichever is later) — but that window extends to six years if income was underreported by more than 25%, and there's no limit at all if a return was never filed or was fraudulent. A clean, monthly reconciliation trail is what makes any of those years easy to defend if it ever comes up.

If You're Doing This by Hand, Don't Rely on Memory

Reconciling from a blank spreadsheet each month is where most of the above errors sneak in — a missed outstanding check from two months ago, a fee you forgot to carry forward. A repeatable template does the carrying-forward for you: iLuvAccounting's free Bank Reconciliation Template is built for exactly this, and every template in iLuvAccounting's Tools Club ships with a built-in AI prompt: attach your finished reconciliation and ask it for a second opinion — does anything look like a duplicate, a transposed number, or a missing entry — before you file it away. That's a check on your work, not a replacement for doing it yourself.