Accounting CSV imports: preventing duplicate transactions before upload

Record file origin, entity, account, date range, timezone, currency, and export date. Keep the untouched original. Determine whether the file contains posted transactions, pending transactions, balances, or a mix.

An export's date column may represent purchase, posting, settlement, or invoice dates. Confirm the meaning before mapping it to the accounting period.

Check bank feeds, integrations, manual entries, and earlier uploads for the same range. Use source transaction IDs where available, with amount, date, and reference as supporting checks.

Two transactions with the same amount can both be valid. An import method that removes every matching amount may erase legitimate repeated purchases.

Verify account, signs, customer or vendor, tax treatment, and required fields. Have the accounting reviewer approve unusual mappings.

For illustration, importing a card payment as a new expense duplicates charges already recorded on the card. A mapping that treats transfers as sales can similarly distort revenue while still matching the bank amount.

Compare row count, gross debits, credits, and relevant balances with source reports. Review rejected rows and duplicate warnings. A successful upload message does not establish complete coverage.

Use the application's documented backup, preview, or testing process when available. Do not upload an uncertain full-year file to production merely to see what happens.

Save the original, reviewed file, mappings, date, user, results, and any corrections. Restrict sensitive contents and avoid including reusable credentials.

Reconcile the affected account afterward and investigate differences at their source. A controlled import should leave the ledger with the intended transactions once each, plus enough evidence to reproduce or repair the process.

Verify whether the source export changed after a reversal or correction. Keep a revised file linked to the earlier upload and identify the affected rows. Reimporting the complete replacement file can duplicate transactions that were already correct.