Everything is matched to zero and the reconciliation still won't tally

You matched everything. The unmatched lists are empty. And the header still shows a difference — or worse, a month you reconciled weeks ago and signed off has quietly opened up again.

This is the design working, not failing, and there is a thirty-second check that proves it.

The 30-second check

Look at the four balances on the reconciliation header, and know which two are yours.

Balance	Who writes it	Does it move on its own?
Cash book opening and closing	BigLedger, from your cashbook lines	Yes. Constantly.
Bank statement opening and closing	You, typed off the bank’s paper	Never. Nothing in the platform writes them.

1. Press Refresh calculated balance. That recomputes the cash book side on demand. If the difference changes, the cash book side had already moved and the screen was showing you an older figure.

2. Compare the cash book closing balance with the figure you remember signing off. If it has moved and the bank’s has not, something landed in the reconciled period after you finished — and the difference you are looking at is real, not cosmetic.

3. Ask when the difference started. If it appears from one particular month onwards and every month before it is clean, that is the signature of a document dated backwards into that month. It is almost never a matching error.

What actually happened

The cash book side is not frozen. It is computed when you create the session — opening is everything before the start date, closing is opening plus the period’s active, non-voided cash book lines — and it recomputes without being asked. Database triggers on the cash book line, on the document header and on the cash document header fire whenever a cash book line is inserted, changed or deleted, or its document is voided, and they rewrite the cash book balances of every active reconciliation for that cash book. Not just the one you have open — a March session you finished weeks ago too.

The bank statement side has no such machinery. It is the one figure on that screen that is purely yours.

So: somebody keyed a receipt in April and dated it 24 March. The trigger fired. Your March cash book closing balance moved. The bank’s did not, because the bank’s statement did not change. A variance you had cleared is open again.

The reconciliation is now telling you the truth: your books and the bank no longer agree for March, and in fact they did not agree before either — you just could not see it. The fix is to account for the new line, not to hunt for a difference among the lines you already matched.

Two related traps on the same screen

Each cash book line carries an open amount — how much of it is still unmatched. That is a stored remainder that each match decrements, not something worked out fresh from the links. It is why a half-matched line can look odd after a link is removed.

A matched line can simply vanish. While a line is matched, the source voucher’s amount cannot be edited — but it can be voided, and a voided line drops out of the cash book balance afterwards. The line disappears from the reconciliation and the balance moves, with nothing on the reconciliation screen to say why.

What to do about it

Refresh the calculated balance and read the difference again.
Find what landed in the window. List the cash book’s lines for the reconciled period and sort by the date they were created rather than the date they are dated. Anything created after the session was is your candidate.
Account for it — match it to a statement line, or recognise it as a genuine timing difference that belongs in the variance.
Do not re-hunt the matched lines. They were right when you matched them and they are still right.

The variance between your books and the bank is not an error to be made to disappear. It is the output of the exercise.

When it is a support matter

The difference does not move after Refresh calculated balance, every visible line is matched to zero, and no line was created after the session. At that point you have exhausted the ordinary explanation, and the residual is worth reporting with the cash book, the period, and the two closing balances written down.

What this page cannot tell you

When the cash book balances were last recomputed. The record carries created and updated dates; the report you printed does not.
Whether every path that lands a line in the window fires the trigger. The triggers on the cash book line, the document header and the cash document header are the ones in the schema; a bulk import or a direct correction may reach the data another way.
How to rebuild a bank statement side. There is nothing to rebuild — it is what you typed, and only you can change it.