How to check an AI-built bank statement spreadsheet

A chat AI writes the answer that seems most likely. It doesn’t add up a column the way a calculator does, and it doesn’t go back to look at the page. So it can misread a digit, skip a line, count a payment twice, or make up a number so that a total comes out right. These are often called AI hallucinations: a made-up row looks just like a real one. Asking the AI to double-check itself doesn’t fix this, because it checks with the same eyes that made the mistake.

For each statement, take the opening balance, add every deposit, take away every withdrawal, and you should land on the closing balance printed by the bank, to the cent. If you don’t, a row is missing, doubled, or misread. This is the first check because it’s quick and it catches a lot.

One warning: if the AI was told the balances must match, it may add a made-up row to force them to. So also do check 3.

Line the statements up in order. The closing balance of March should be the opening balance of April. If it isn’t, a month or a page is missing, or one was read twice. A single statement can balance on its own while a whole month is gone, so this check catches what check 1 can’t.

Count the rows on each page of the PDF and compare with the rows the spreadsheet has for that page. A different count means a row was skipped, split in two, or invented.

Statements often overlap by a few days, and a downloaded statement can repeat a printed one. Sort by date and amount, and look for the same payment twice on the same day. Then go back to the PDF: two real coffees at the same price are fine; one coffee read twice is not.

Money moved from checking to savings is not income or spending. It should appear once as money out of one account and once as money in to the other, for the same amount, and both should be filed as a transfer. If only one side is there, a statement is missing. If a transfer is filed as income, your income is overstated.

AI sometimes reads a withdrawal as a deposit, especially when the statement uses one column with minus signs, or puts “CR” and “DR” after the amount. Spot-check refunds, returned payments and fees: these are the rows most often flipped. A flipped row moves the total by twice its amount.

Many statements print dates without a year. A December statement that runs into January can get January’s rows filed in the wrong year. Check the rows on either side of January 1st, especially if the spreadsheet is for taxes.

On scans and photos, an 8 can become a 3, a 1 can become a 7, and a decimal point can vanish. Check 1 will usually tell you a statement is off; to find the row, compare the larger amounts against the PDF first, since a missing decimal point makes an amount a hundred times too big.

Sort by description. The same business should be in the same category on every row, unless you really did buy different things there. AI often files the same gas station as fuel one month and groceries the next.

Checks 1 to 8 prove the rows match the statements. Only check 9, and your own judgment, tell you the categories are right. A spreadsheet can balance perfectly and still have the wrong spending in the wrong place. We explain why in Why a bank statement that ties out can still be wrong.

1. Opening plus transactions equals closing, for every statement.
2. Each closing balance equals the next opening balance.
3. Row counts match the PDF, page by page.
4. No duplicates where statements overlap.
5. Transfers between your own accounts on both sides, filed as transfers.
6. Refunds, returns and fees not flipped.
7. Year-end dates in the right year.
8. Large amounts checked against the PDF on scans.
9. Each merchant in the same category every time.