By Manvinder Sidhu, Co-founder, Ezyiah
Short answer: If your bank is reconciled in Xero but the BAS doesn't match, the problem is almost never the reconciliation. Xero builds the BAS from the GST tax rates and dates on each transaction, which reconciliation doesn't check. The usual causes are wrong GST codes, duplicates from a CSV import or feed backfill, transactions dated in the wrong period, backdated edits after you reviewed, the wrong GST accounting basis (cash or accrual), GST-inclusive or exclusive amount errors, and balance sheet items such as director loans coded as expenses. Use Xero's GST Audit Report to trace each BAS figure back to transactions, fix the transactions, and don't adjust the final number.
Why can a reconciled file still produce the wrong BAS?
Reconciliation checks that money in and out matches the bank. The BAS asks a different question: how much GST was collected and paid in the period. Xero answers it from the tax rate on each line and its date, not from whether it's reconciled. A transaction can be perfectly reconciled and still have the wrong GST code. That's the gap behind most "BAS not matching" searches.
What are the 7 most common causes?
- Wrong GST codes. GST claimed on wages, super, bank fees or GST-free items, or overseas subscriptions coded incorrectly. See GST on overseas software subscriptions.
- Duplicates. A CSV import overlapping a feed backfill. Both copies reconcile, but GST is doubled. See duplicate bank transactions after a CSV import.
- Wrong period. Transactions dated into the wrong quarter, often from statement date formats.
- Backdated edits. Journals or unreconcile-and-redo changes made after you reviewed. See unreconcile and redo in Xero.
- Cash vs accrual basis. The GST basis in Xero's settings differs from the basis the business is registered for with the ATO. Businesses under $10 million turnover can choose cash accounting for GST.
- Inclusive vs exclusive amounts. Lines entered as tax-exclusive when the amount already includes GST, or the reverse.
- Balance sheet items coded as expenses. Director loans, transfers and asset purchases coded to expense accounts with GST. See director loans in bank feeds.
How do you fix a BAS that doesn't match?
- Run the GST Audit Report for the period and compare it with the BAS figures.
- Sort by tax rate and look for codes that don't fit the account (for example GST on wages).
- Check the weeks around any feed outage or CSV import for duplicates.
- Check the GST basis in the Xero settings against the ATO registration.
- Look for edits and journals dated in the period but made after your review.
- Fix the transactions, re-run the BAS and confirm the figures now trace back.
Never force the BAS to match by changing the final figure. It hides the cause and the same problem comes back next quarter. If an error is in a BAS you've already lodged, see how long you can amend a BAS.
How Ezyiah handles BAS differently
Ezyiah is an AI bookkeeper with its own double-entry ledger, built for Australian cash-basis BAS. It reconciles live bank feeds daily, codes GST with AI, and remembers your corrections with AI Memory. Scan Similar Transactions fixes a repeated coding error across the file. The BAS builds from the same books throughout the quarter, so a mismatch shows up while there's time to fix it. Your accountant reviews and approves before lodgement.
If you're weighing up a switch, see Ezyiah vs Xero, or how it works for business owners and accounting firms.
Frequently asked questions
Why doesn't my Xero BAS match my reconciliation?
Because the BAS is built from GST codes and transaction dates, not from reconciliation. A reconciled transaction can still have the wrong GST code or sit in the wrong period.
Why did my BAS figures change after I'd checked them?
Usually because of a backdated edit, a journal, or a bank feed that brought in earlier-dated transactions after your review.
How do I check GST in Xero before lodging?
Run the GST Audit Report for the period and trace each BAS figure back to its transactions.
Can I just adjust the BAS figure to match?
No. Fix the underlying transactions so the BAS is right and defensible.
