Why format matters before you start
Bank statements arrive in more than one shape. Some are genuinely machine-readable exports — CAMT.053, MT940, OFX, QFX, QBO and QIF are all structured formats designed to be parsed by software, with clearly defined fields for dates, amounts and descriptions. Others are effectively pictures of a statement: a PDF or a screenshot, formatted for a human to read, not a program.
Structured formats convert cleanly because the data is already labeled — a program can find “this is the amount” and “this is the date” without guessing. A PDF has no such labels; extracting a table from one relies on interpreting a visual layout, which is a fundamentally different, and less reliable, problem. If you have a choice when exporting from your bank, a structured format is worth choosing over a PDF.
What conversion preserves
A good conversion keeps the transaction data exactly as reported: dates in a consistent format, amounts as exact decimal values rather than rounded approximations, and descriptions or payee names as supplied. It shouldn't apply currency conversion, estimate missing balances, or reformat text in a way that changes its meaning — spreadsheet software can otherwise misinterpret certain text as a formula, so that risk needs to be neutralized rather than ignored.
What it can't do is add information the source file doesn't contain. If your bank's export omits a value date, or QIF doesn't specify a currency, the converted file will have that field empty rather than guessed.
CSV or XLSX?
CSV is a plain-text, universally compatible format: every spreadsheet program, accounting tool and script can read it, and it holds up well for large files or when you need to import the data somewhere else. XLSX (Excel) adds native cell types — real dates and numbers instead of text — plus multiple sheets, which is useful when you want to open the file directly and start working with it, including any statement metadata like opening and closing balances on a separate sheet.
There's no universally correct choice. If you're feeding the data into another system, CSV is usually simpler. If you're going to work in Excel directly, XLSX saves a formatting step.
Verify before you rely on it
Regardless of format or tool, it's worth spot-checking a converted statement against the original before using it for anything that matters — reconciliation, taxes, or accounting entries. Compare a handful of transactions and the opening and closing balances. This matters more for edge cases: batched entries, unusual characters in descriptions, or ambiguous dates can all be handled differently depending on the source format and the conversion tool.