Every conversion is checked against available statement balances; mismatches are flagged before you download.
The check
Where a bank statement supplies an opening balance and a closing balance, these provide an arithmetic reference. After extraction, NoRekey sums every transaction amount and checks that opening + all transactions = closing, to the penny. Only a statement that passes is tagged balanced.
Why it matters
Extraction mistakes in this category of tool are rarely random noise — they're a dropped row, a flipped sign, or a misread decimal. An isolated amount error usually changes the total. Offsetting errors can cancel out, however, and an incorrect date or description need not change the arithmetic. A balanced result is a useful check, not proof that every field is correct.
What "needs review" means
If the rows don't reconcile, the conversion is clearly flagged — in the converter, and in your history. You can still open and export the data (it's often fine except one identifiable row), but you'll know to compare against the original before importing. Nothing unbalanced is ever exported silently.
When the check can't run
Some statements don't print an opening or closing balance — certain card statements and exports omit them. In that case there's nothing to verify against, and the conversion completes without a balanced tag rather than pretending to a guarantee it can't make.