What each format actually is
OFX (Open Financial Exchange) is a structured format built specifically for financial data. It carries dates, amounts, transaction types, and a unique transaction ID for each line. QFX is Intuit's flavor of OFX, and QBO is the QuickBooks Web Connect variant. QIF is an older, related plain-text format still accepted in some places.
CSV (comma-separated values) is just a plain text table. Each row is a transaction, each column is a field like date, description, or amount. There is no fixed layout, so one bank's CSV can look nothing like another's.
The key difference is self-description. An OFX file tells the software how to read it. A CSV does not, so you have to map the columns yourself during import.
When to use OFX
Reach for OFX (or QFX/QBO) when your accounting software offers a direct import for it and your bank provides the file. Because each transaction carries a unique ID, the software can recognize records it has already seen and reduce duplicate entries when you import overlapping date ranges.
OFX also encodes amounts and transaction types in a fixed way, so there is less ambiguity about whether a number is a debit or a credit. That means fewer sign errors and less cleanup after the import.
One caution: QBO and QFX files sometimes carry a bank identifier (often referred to as an INTU.BID or a routing/bank ID). If that identifier does not match what your software expects, the import can be rejected. This is a known friction point when a file was produced for a different bank profile.
When to use CSV
Use CSV when OFX is not available, when you need to review or edit the data before importing, or when you are moving transactions into a spreadsheet rather than directly into accounting software. CSV opens in Excel or Google Sheets, so you can sort, filter, split, and correct rows freely.
CSV is also the more universal fallback. Almost every tool can export and import it, even if the column layout differs. The trade-off is the manual mapping step: you tell the software which column is the date, which is the amount, and how the date is formatted.
Watch the details. Date formats (day-month-year versus month-day-year), single amount columns versus separate debit and credit columns, negative signs, and thousands separators all cause import errors if they are misread. Confirm these before you commit the import.
How to choose and avoid common problems
If your software supports a direct OFX/QFX/QBO import and your date range is clean, OFX usually gives a smoother result with less manual coding. If you need to inspect, clean, or reshape the data first, CSV gives you control.
To avoid duplicates, import non-overlapping date ranges and let the software's matching or bank-feed reconciliation catch repeats. OFX's transaction IDs help here; CSV imports rely more on your care with date ranges.
To avoid miscoded amounts, verify the sign convention before importing. Confirm whether a single amount column uses negatives for money out, or whether debits and credits sit in separate columns. Reconcile the imported opening and closing balances against the statement as a final check.
If your bank only gives you a PDF statement, you can convert it to either format. Converting to CSV lets you review before import; converting to OFX/QFX/QBO can enable a direct import into QuickBooks, Xero, or Wave when those tools accept the format.