26 January 2026

5 Bookkeeping Mistakes That Can Get You in Trouble With the ATO

Running a small business in Australia comes with plenty of moving parts — and unfortunately, the Australian Taxation Office (ATO) doesn’t give much leeway when bookkeeping obligations are missed. Many ATO issues don’t start with fraud or intentional wrongdoing. They start with small bookkeeping mistakes that snowball over time. Here are five common bookkeeping mistakes we regularly see at Open Bookkeeping Australia (OBA) — and how you can avoid them.

1. Lodging BAS Late

Lodging your Business Activity Statement (BAS) late is one of the fastest ways to attract unwanted ATO attention.

Late BAS lodgements can lead to:

Failure to Lodge (FTL) penalties
Interest charges
ATO compliance reviews
Payment plans being revoked

Even if you can’t pay your BAS on time, lodging on time is still critical. The ATO is generally far more flexible when returns are lodged but unpaid than when they are ignored altogether.

Tip: Using a registered BAS agent can often give you extended lodgement deadlines, providing more breathing room.

2. Not Keeping Proper Records

The ATO requires businesses to keep records for at least five years. This includes:

Sales invoices
Expense receipts
Bank statements
Payroll and superannuation records

Poor record-keeping makes it difficult to:

Defend deductions
Reconcile BAS correctly
Respond to ATO queries
Accurately track business performance

In an audit, “I couldn’t find the receipt” usually isn’t accepted as a valid explanation.

Tip: Cloud accounting software like Xero, combined with regular reconciliations, dramatically reduces record-keeping risks.

3. Not Paying Superannuation on Time

Superannuation is not optional, and missing deadlines can be extremely costly.

If super isn’t paid by the due date:

The Superannuation Guarantee Charge (SGC) applies
You lose the tax deduction
Penalties and interest are added
Directors can become personally liable

Even being one day late can trigger the SGC.

Tip: Automating payroll and super through compliant software helps ensure deadlines are met every time.

4. Not Separating Business and Personal Expenses

Mixing personal and business expenses is a very common issue — especially for sole traders and small companies.

Problems this creates include:

Incorrect GST claims
Overstated deductions
Complicated reconciliations
Increased audit risk

The ATO expects business transactions to be clearly identifiable. Regularly using personal accounts for business spending can raise red flags.

Tip: A dedicated business bank account and card make bookkeeping cleaner, faster, and far more defensible.

5. Failing to Withhold PAYG Withholding (PAYGW)

If you employ staff or pay directors, you are generally required to withhold PAYG tax and remit it to the ATO.

Failing to withhold or remit PAYGW can result in:

ATO penalties
Director Penalty Notices (DPNs)
Loss of payment arrangement options
Serious cash flow stress

PAYGW issues are taken very seriously by the ATO, especially when combined with late BAS lodgements.

Tip: Accurate payroll setup and regular reviews ensure PAYGW is calculated and reported correctly from day one.

How Open Bookkeeping Australia Can Help

Most ATO issues are preventable with the right systems and support in place.

At Open Bookkeeping Australia, we help small businesses:

Stay on top of BAS and compliance deadlines
Keep clean, audit-ready records
Run compliant payroll and super
Avoid ATO penalties before they start

If you’re unsure whether your bookkeeping is putting you at risk, it’s far better to address it early.

Need Help Getting Your Bookkeeping Back on Track?

If you’d like a clear picture of where your bookkeeping stands — or want help avoiding ATO headaches — get in touch with Open Bookkeeping Australia.

Contact us today to discuss how we can support your business.