> For the complete documentation index, see [llms.txt](https://www.zerabooks.com/help/llms.txt).
# How ZeraBooks proves a statement
Every statement you upload is checked against its own printed opening and closing balances, so you know the transactions are complete before you rely on them.
## Why statements prove your books
A bank statement prints an opening balance and a closing balance. If every transaction between them is in your books, the numbers must add up. ZeraBooks uses that to prove each statement, instead of asking you to tick off lines one by one.
## The three checks
When you upload a statement, ZeraBooks reads the printed opening and closing balances along with the transactions. A statement **ties** when all three checks pass:
1. **The statement adds up.** Opening balance + every transaction − closing balance = 0.
2. **The chain holds.** The opening balance matches the previous statement's closing balance for the same account.
3. **The ledger agrees.** Your ledger balance for the account equals the printed closing balance.
Open any month in **Accounting** › **Reconciliations** to see the checks side by side. For a bank account, the tiles read **Deposits**, **Withdrawals** and **Net**; for a credit card, **Payments**, **Charges** and **Net**. Each tile compares the **Statement** with the **Ledger** and shows the **Difference**.
## When a statement doesn't tie
A statement that doesn't add up still imports. The upload shows a warning that starts "Statement does not tie: opening + transactions − closing = X. Imported anyway", and the month shows an orange **!** in Reconciliations. An orange dot also appears next to **Reconciliations** in the left navigation.
Common causes:
- a transaction or a printed balance was misread;
- a line is missing, or was read twice;
- the previous month's statement hasn't been uploaded yet.
Follow [Fix a month that doesn't tie](https://www.zerabooks.com/help/reconciliations/fix-a-month-that-doesnt-tie), or let AI check the statement against the document with [Verify a statement with AI](https://www.zerabooks.com/help/reconciliations/verify-a-statement-with-ai).
{% hint style="info" %}
**Tip:** If the whole statement was read badly, it's quicker to remove it and upload a clearer copy. See [Remove a statement](https://www.zerabooks.com/help/banks-and-cards/remove-a-statement).
{% endhint %}
## Frequently Asked Questions
Does a statement have to tie before it's imported?
No. It always imports, with a warning if it doesn't tie. You fix the difference afterwards in Reconciliations.
Do categories affect whether a statement ties?
No. Categories don't change an account's balance. Only amounts, dates, missing or extra lines, and printed balances do.
Why does the chain check fail when the statement itself adds up?
This statement's opening balance doesn't meet the previous statement's closing balance. A statement may be missing between them, or one of the printed balances was misread.
Why did the signs on my statement get flipped?
If a statement only ties with the amounts reversed, ZeraBooks flips them and adds a warning to the import. Check the register against the document.
Where do I sign off a statement that ties?
In Reconciliations. Click **Finalize…** on the month. See [Finalize a month](https://www.zerabooks.com/help/reconciliations/finalize-a-month).
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