The balance check failed: find the error from the difference

A failed check is good news

When opening balance + credits − debits does not land on the closing balance printed on the statement, the check has done its job: it has stopped a wrong number before it reached the books. Found now, the error takes minutes to fix. Found at month-end reconciliation, it takes an afternoon.

The difference is also more than a number to note down. Its size usually tells you what kind of error you are looking at, and where to find it. This guide shows how to read it.

Step zero: can this statement be checked at all?

The check needs three things from the document: the opening balance, the closing balance and every transaction in between. If one of them is missing, a difference does not mean an error. Rule these cases out first:

• One page of a longer statement. The opening balance is on the first page and the closing balance on the last one, so a single page or a single photo cannot balance. Upload the whole statement as one PDF: the scanner app on any phone merges photos into a single file.
• A page missing from the PDF you received. Compare the "carried forward" total at the bottom of each page with the "brought forward" total at the top of the next one. Where they do not match, a page is missing.
• Two accounts or two currencies in the same file. Each account has its own opening and closing balance. Split them and check each one separately.
• An interim statement printed mid-period, with no closing balance: there is nothing to compare against yet.

Read the difference: six fingerprints

Call D the difference between the calculated closing balance and the one printed on the statement. Then test these patterns, in this order:

1. D equals one transaction → a line is missing or counted twice. If the calculated balance is too high, look for a debit of that amount that was skipped, or a credit counted twice. If it is too low, the opposite. Search the statement for that exact amount.
2. D is twice a transaction → a sign is flipped. A payment read as a receipt, or the other way round, moves the balance by double its value. Halve D and look for a transaction of that amount in the wrong column.
3. D is divisible by 9 → two digits swapped, or a decimal point shifted. Swapping two adjacent digits always produces a difference divisible by 9: 54.10 read as 45.10 is off by 9.00. So does a shifted decimal point: 1,250.00 read as 125.00 is off by 1,125.00, which is 9 × 125. It is one of the oldest checks in bookkeeping, and it works just as well on OCR errors.
4. D is a single digit followed by zeros (0.05, 5.00, 500.00) → one digit misread. On scans the usual suspects are 3 and 8, 1 and 7, 5 and 6. Look for an amount where that digit, in that position, could have been read the wrong way.
5. D equals the opening balance or a page subtotal → a balance was read as a transaction. Rows such as "Balance brought forward" or "Total this page", extracted as movements, throw the result off by exactly their value.
6. D equals the last fees or interest → a line outside the table was skipped. Charges, interest and taxes are often printed below the transaction table, in a separate summary box. Check the bottom of the last page.

If none of the six fits, the cause is often two errors that partly cancel each other out. In that case the running balance is the fastest way in.

Walk the running balance to find the exact row

Most statements print a balance after each transaction. That column lets you find the wrong row without re-reading the whole statement:

1. Start from the opening balance.
2. For each row, add the credit or subtract the debit, and compare the result with the balance printed on that row.
3. The first row where the two stop matching is where the error is: in that row, or in a row missing just before it.

In Excel this takes two extra columns: one with the previous balance plus the credit minus the debit, and one that compares it with the printed balance. The first mismatch is your row. A good converter uses the same column automatically: when the running balance proves that a debit and a credit were swapped, it can put them back in the right column before the check even runs.

What a zero difference proves, and what it does not

A zero difference is strong evidence: it rules out missing lines and most misread amounts. It does not check dates or descriptions, and in rare cases two errors can offset each other exactly. Nor does it say anything about whether the document itself is genuine: it is arithmetic on the extracted data, not an audit.

That is why it is worth keeping a record of the check alongside the file: which statement, which period, which balances and what result.

How myocr.app handles it

Every bank statement converted on myocr.app goes through this check automatically. When the balances match you see it straight away; when they do not, you see the exact difference, so you can apply the patterns above immediately. Registered users can also download CSV for QuickBooks and Xero, OFX, and a one-page Balance Check Report with the balances, the result and a public verification page. In the Excel add-in, the same check is written into the sheet next to the transactions.