How to avoid importing duplicate transactions in QuickBooks

Work in date ranges

The simplest way to avoid duplicates is to convert and import whole date ranges that do not overlap. If a range is already in QuickBooks and you want to import it again, delete the existing transactions for that range first.

IIF files

QuickBooks does not check IIF files for duplicates: every transaction in the file is added, even if the same transaction is already in QuickBooks. Make sure each IIF file covers only transactions that are not in QuickBooks yet.

QBO files

Each transaction in a QBO file has a unique ID (FITID). QuickBooks remembers the IDs it imported for each account and skips a transaction whose ID it has seen before, even if you deleted that transaction.

ProperConvert sets the ID this way:

• If your file has transaction IDs (many bank QBO, QFX and OFX files do), ProperConvert keeps them. Use them only if your bank's IDs are unique across all files, not just within one file.
• Otherwise, a new ID for every conversion. QuickBooks never skips a transaction, so you can delete transactions and import them again. But if two files overlap, the overlapping transactions are imported twice.

Two settings change this. Choose File > Settings..., open the Format specific tab, and go to the QBO/QFX/OFX page:

• Regenerate References: ignore the IDs from your file and make new ones. Use it if your bank's IDs repeat.
• Deterministic references: when ProperConvert makes the IDs (your file has none, or Regenerate References is on), make each ID from the date, amount and payee, so the same transaction gets the same ID in every file. QuickBooks then skips transactions from overlapping files that it already imported. Two transactions with the same date, amount and payee get the same ID, so QuickBooks imports only one of them. And once a transaction has been imported, QuickBooks skips it in later files even if you deleted it from QuickBooks: to import it again, turn this setting off.