BAS preparation
How Do I Prepare Old Bank Statements for BAS Catch-Up Work?
Reviewed 12 September 2026
Short answer
Short answer
Confirm the BAS periods and entities with your registered tax or BAS agent, then collect every relevant account statement. Convert each account into a separate chronological transaction file, reconcile the rows to the printed balances, identify transfers and likely income or expenses, and attach source documents where available. Treat automatic categories as a first pass only. GST treatment and final BAS coding should be decided by a qualified professional.
Bank statement conversion removes data preparation work. It does not replace the records, judgement or professional review needed for a BAS.
Prepare a complete, reviewable transaction history
Work period by period and account by account. If a statement is missing, disclose the gap instead of assuming that adjacent balances prove no activity occurred.
Separate transfers before calculating income or expense totals. Merchant categories can speed up review, but the transaction description alone may not establish GST treatment or business purpose.
Step by step
- 01
Confirm scope with your agent
List the entities, BAS periods, accounts and source documents they require.
- 02
Create a statement inventory
Mark available and missing periods for every bank account and card.
- 03
Convert and reconcile
Produce one checked transaction history per account and retain links to source PDFs.
- 04
Prepare review notes
Flag transfers, uncertain merchants, missing evidence and transactions needing GST decisions.
Checks before you rely on the spreadsheet
- A qualified agent confirmed the BAS scope.
- All relevant accounts and periods are listed.
- Each converted statement reconciles.
- Categories are not presented as final GST treatment.
Questions people ask
Can bank statement categories calculate my BAS?
No. Categories can organise transactions, but BAS and GST treatment require additional evidence and professional judgement.
What if a statement month is missing?
Record the gap and ask the bank for the missing statement. Do not silently infer that no transactions occurred.
Should I send the original PDFs to my BAS agent?
Yes, unless they tell you otherwise. The CSV is a working file and the PDFs remain the source statements used for checking.