Bank reconciliation has a reputation problem. It sounds like an afternoon of squinting at spreadsheets, and if you leave it for three months, it is. Done monthly, though, it's one of the quickest jobs in bookkeeping — and the one that stops small errors turning into a set of accounts nobody can rely on.

At heart, reconciliation is simple. Your bank statement is a record of what actually happened to your money. Your bookkeeping is a record of what you think happened. Reconciling means proving the two agree, and being able to explain every difference that says they don't.

1. Set your cut-off and gather the paperwork

Pick a period with a fixed end date, usually a calendar month, ending on the last day the statement covers. Everything you reconcile must fall inside that window. Reconciling to "roughly the end of the month" is how months get missed.

Before you start, have these in front of you:

• the bank statement or bank feed for the period, including the opening and closing balances
• sales invoices you issued, plus the receipts or remittances showing which ones were paid
• supplier invoices and receipts for everything that went out
• your bookkeeping records — a spreadsheet, or software such as Xero, QuickBooks or FreeAgent

If you use cloud software, the bank feed will have imported most transactions already. Don't assume that makes it a formality. Feeds create their own problems, which we'll come to.

2. Check the opening balance, then tick off line by line

Before touching a single transaction, confirm the opening balance in your records matches the opening balance on the statement. If it doesn't, the problem sits in an earlier period. Fix it there first, or you'll spend the session chasing an old mistake through new numbers.

Then work down the statement in date order and tick each line off against your records. Two habits make this much faster:

• Don't jump around. Date order is the only reliable way to spot what's missing.
• Read the bank's description properly. "FPS 12/03 ACME LTD" is a clue. So is a reference number, even a partial one.

Software will suggest matches automatically, and most of the time it's right. Approve them one at a time anyway, at least for the first few months. Bulk-approving a feed is where duplicates and misposted expenses quietly hide.

3. Match each transaction to an invoice or receipt

For money in, find the sales invoice and the payment that settled it. For money out, find the supplier invoice or the receipt. The amounts should match — but not always exactly, and that's where people get stuck.

These are the usual reasons a genuine transaction won't line up:

• bank charges, card fees and interest you haven't recorded yet
• standing orders and direct debits you'd forgotten were set up
• a payment that cleared the bank in a different month from the one you posted it in
• foreign currency transactions, where the bank's rate differs from the one you used
• a customer paying two invoices together, or part-paying one

None of these is a mistake by the bank. They're entries your records are missing, and they need adding.

4. Chase missing entries before you guess

Missing paperwork is the most common reason a reconciliation stalls. Money leaves the account and there's no invoice, no receipt and no memory of what it was for.

Don't leave a hole, and don't invent a figure you can't support. Try this order:

1. Search your email for the amount or the supplier's name.
2. Ask the supplier for a duplicate invoice. Most send one the same day.
3. Check the bank description for a reference, a phone number or a trading name you half recognise.
4. Cross-check your diary, card receipts or delivery notes for that week.

If you genuinely can't find it, record an estimated expense with a note explaining what you did and why, then correct it when the paperwork appears. Where the tax treatment matters — a large purchase, something that might be capital rather than revenue, or a cost that's part personal and part business — speak to an accountant rather than guessing.

5. Deal with duplicates, then prove the closing balance

Duplicates usually come from one of two places: a transaction entered by hand and then imported again through the bank feed, or a payment recorded twice from two different receipts or screenshots.

Look for a payment on the same date for the same amount, or two entries with slightly different descriptions but identical references. Delete the duplicate, not the original — and check whether it was also matched to an invoice, because that will throw your aged debtors out as well.

Once every line is ticked, compare the closing balance on the statement with the closing balance in your records. They should agree. If they don't, the gap itself tells you where to look:

• A small, round difference — a bank charge or interest you haven't posted.
• Exactly double an amount — a duplicate.
• A payment you've recorded that hasn't cleared — a timing difference, not an error. It will clear next period.

If you can't explain a difference in one sentence, you haven't finished looking. Plugging it with an "adjustment" entry just hides it somewhere you'll forget to check.

Make the next one easier

Reconcile monthly, on the same date, and the job stays small enough to finish over a coffee. File receipts as you go — a photo taken the day you spend is worth an hour of hunting later. Reconcile to a fixed cut-off rather than "about the end of the month", and when something doesn't match, write one line explaining why. Future you will be grateful.

That's the whole process. Unromantic, but it's what makes your figures worth something when a lender, an accountant or HMRC asks a question. If your setup is complicated — several accounts, VAT, or a mix of personal and business spending — get a bookkeeper or accountant to review it once. It costs far less than unpicking a year of mismatched entries.

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