Know exactly what to check before you lodge each quarter. Avoid penalties, errors and last-minute stress.
Step-by-Step
Click each step to expand. Work through all 10 before lodging.
Know your lodgement frequency before anything else. Most small businesses lodge quarterly, but some lodge monthly. Check your current period dates in ATO Online Services or in Xero. The standard due date is 28 days after the end of the quarter. If a registered tax agent lodges on your behalf, you may be eligible for an extended deadline.
This is the most important step and the one most people skip when they are in a hurry. Every transaction in your accounting software needs to match your bank statement. If there are uncategorised transactions sitting in Xero, sort them before you do anything else. Unreconciled accounts mean your GST figures will be wrong.
GST is 10% on most taxable sales. Check that every sale has been coded correctly, including any GST-free sales like fresh food, medical services or exports. On the expenses side, you can only claim input tax credits on genuine business expenses. Personal costs cannot be claimed, and the ATO looks for this specifically.
Add up total sales for the period across all payment types: cash, EFTPOS, invoices and online payments. Include deposits or prepayments received during the period. Exclude any income that is GST-free or out of scope. Your total should reconcile with what landed in your bank account, adjusting for timing differences between invoicing and receiving payment.
Review every business expense for the period. For any GST credit you want to claim on a purchase over $82.50, you need a valid tax invoice, not just a receipt. Remove any personal expenses from your records before lodging. If you made any large capital purchases during the quarter, check how they need to be treated before including them.
If you employ staff, your BAS includes PAYG withholding obligations. Confirm total wages paid during the period and check that the withholding amounts reconcile with your payroll software. Make sure all payroll events have been lodged through Single Touch Payroll. Super should be calculated at 12% and reported correctly.
If you run a tradie or construction business with subcontractors, check your TPAR obligations separately. See our guide for tradies and contractors for more detail on contractor reporting.
PAYG instalments apply if you have business or investment income outside of employment. Check whether an instalment amount or rate is showing on your BAS. You can pay the ATO suggested amount or vary it if your income has changed significantly. If you vary it and underestimate, the ATO can apply penalties.
Before lodging, look at the total. Does the amount owing or refundable make sense relative to your revenue for the quarter? Compare it to the previous quarter. Large unexplained variances are a flag. If something looks off, investigate before lodging. Amending a BAS after the fact is more work than getting it right the first time.
Lodge through ATO Online Services, Xero, or through your registered tax agent. Pay any amount owing by the due date to avoid general interest charge. Save a copy of the lodged BAS and your payment confirmation. Set a reminder in your calendar for the next period start date straight away, while it is fresh.
Keep all invoices, receipts and bank statements for the period. The ATO requires you to hold records for five years from the date of lodgement. Digital storage is fine. If your books are behind and you are struggling to get organised, our catch-up bookkeeping service can help you get back on top of it quickly.
Watch Out For
Lodging BAS is routine for a bookkeeper. For business owners doing it themselves, these come up regularly.
The ATO specifically reviews for personal expenses coded as business costs. Groceries, clothing, private travel and personal phone bills cannot be claimed. If you are unsure whether something qualifies, leave it out and ask your bookkeeper.
The ATO charges a Failure to Lodge penalty and general interest on late amounts. If you know you are going to be late, contact the ATO before the due date, not after. Proactive contact almost always results in better treatment than being chased.
A payment receipt is not the same as a tax invoice. For any purchase over $82.50 where you want to claim a GST credit, you need a proper tax invoice showing the supplier ABN, the GST amount, and a description of what was purchased.
Every payment you receive needs to be reported, including cash. Unreported cash income is one of the most common triggers for an ATO audit. It is not worth the risk.
If you invoice in one period and receive payment in the next, make sure you are counting it only once across your BAS periods. This is a common error for businesses that use invoice-based accounting.
A single transaction coded to the wrong account can throw your GST figures out without you realising. This is one of the reasons reconciliation matters. Review your account coding before you lodge, not after.
Reference
| Quarter | Period | Standard Due Date | Via Registered Agent |
|---|---|---|---|
| Q1 | 1 Jul to 30 Sep | 28 October | Extended deadline |
| Q2 | 1 Oct to 31 Dec | 28 February | Extended deadline |
| Q3 | 1 Jan to 31 Mar | 28 April | Extended deadline |
| Q4 | 1 Apr to 30 Jun | 28 July | Extended deadline |
FAQ
AffordBooksTax handles BAS preparation and lodgement as a standalone service, starting from $99 per quarter. Pair it with our monthly bookkeeping and your accounts will always be reconciled and ready before every lodgement deadline. We reconcile your accounts, check your figures, lodge on time and give you the extended agent deadline as standard. No lock-in contract.
