An American Express billing statement is a card statement, not a bank account statement, and that changes what a converter has to do. There is no running account balance beside each row to check your work against. Instead Amex prints an Account Summary near the top — Previous Balance, Payments and Credits, New Charges, Fees, Interest Charged and New Balance — and that arithmetic is the only reconciliation the document offers. The transaction detail below it is grouped rather than listed flat: charges are broken out by Card Member on accounts with supplementary cards, and rows carry merchant name, location and sometimes a second line of trip or reference detail. Foreign spend prints the original currency amount alongside the dollar figure.
- The Account Summary is the checksum — Previous Balance − payments/credits + new charges + fees + interest must equal New Balance, and that is what the conversion is measured against.
- Grouped detail sections are flattened into one continuous transaction list, so charges on supplementary cards do not get lost between section headers.
- Multi-line merchant detail is rejoined rather than turned into extra rows with no amount attached.
- The Balance column will be empty in the CSV for a card statement, because Amex does not print a per-row balance — the summary check stands in for it.