For many Perth business owners, lodging a Business Activity Statement (BAS) can feel stressful, especially when GST calculations are involved. Even small GST errors can lead to incorrect BAS reporting, ATO adjustments, penalties, and unnecessary administrative headaches.

Whether you’re a sole trader, contractor, tradie, café owner, retailer, or growing company, reducing GST mistakes before lodging your BAS can save time, money, and stress.

At JGW Bookkeeping Services, we regularly help Perth businesses identify GST errors, improve bookkeeping processes, and submit accurate BAS reports with confidence.

Why GST Accuracy Matters

Goods and Services Tax (GST) is collected on behalf of the Australian Government and reported through your BAS.

Incorrect GST reporting can result in:

• BAS amendments
• ATO audits and reviews
• Overpayment or underpayment of tax
• Penalties and interest charges
• Cash flow disruptions

Accurate GST records help ensure your BAS reflects your true business activity and keeps your business compliant with ATO requirements.

Common GST Mistakes Perth Businesses Make

Many GST errors occur because of simple bookkeeping oversights rather than intentional mistakes.

Claiming GST on GST-Free Purchases

Not all business expenses include GST.

Common GST-free purchases may include:

• Basic food items
• Some medical services
• Certain education expenses
• Bank fees and charges

Claiming GST credits where no GST was charged can lead to incorrect BAS reporting.

Incorrectly Categorising Expenses

Using the wrong tax code in accounting software can result in:

• Overclaimed GST credits
• Underreported GST collected
• BAS discrepancies

This is particularly common when setting up new suppliers or entering transactions manually.

Mixing Personal and Business Expenses

Many small business owners use the same bank account or credit card for both personal and business spending.

This can create:

• GST reporting errors
• Difficulty during audits
• Inaccurate financial records

Separating business finances significantly reduces bookkeeping mistakes.

Missing Supplier Tax Invoices

To claim GST credits, businesses generally need valid tax invoices for purchases over A$82.50 (including GST).

Missing documentation can result in:

• Disallowed GST claims
• Additional ATO scrutiny
• Time-consuming record retrieval

Reporting GST in the Wrong Period

GST should generally be reported in the correct BAS reporting period.

Common issues include:

• Late-entered invoices
• Duplicate transactions
• Backdated expenses
• Unreconciled accounts

These mistakes can distort GST calculations and create BAS inconsistencies.

Also Check: BAS Preparation in Perth: What Local Businesses Need to Know

How to Reduce GST Errors Before Lodging BAS

1. Reconcile Your Bank Accounts Regularly

Bank reconciliations help identify:

• Missing transactions
• Duplicate entries
• Incorrect GST coding
• Unrecorded expenses

Monthly or weekly reconciliations make BAS preparation much smoother.

2. Review GST Codes Carefully

Before lodging your BAS, review transaction coding to ensure:

• GST purchases are correctly classified
• GST-free expenses are properly coded
• Sales transactions include the correct GST treatment

Accounting software can automate coding, but manual reviews remain important.

3. Keep Digital Copies of Tax Invoices

Maintain organised records of:

• Supplier invoices
• Receipts
• Contractor payments
• Asset purchases

Cloud-based storage systems make it easier to retrieve documents if required by the ATO.

4. Separate Business and Personal Finances

Using dedicated business accounts helps:

• Improve bookkeeping accuracy
• Simplify GST reporting
• Reduce reconciliation time
• Strengthen audit readiness

Many GST mistakes stem from mixed-use transactions.

5. Check Large or Unusual Transactions

Before lodging BAS, carefully review:

• Equipment purchases
• Vehicle expenses
• Deposits and refunds
• International transactions
• Capital asset purchases

These transactions often require special GST treatment.

6. Verify Payroll and GST Reporting

Although wages themselves do not attract GST, payroll-related entries can affect your financial reporting.

Ensure:

• Payroll records are accurate
• PAYG withholding figures align with payroll reports
• Superannuation obligations are up to date

Accurate payroll records contribute to overall BAS accuracy.

Signs Your BAS May Need a Second Review

Consider reviewing your BAS more closely if:

• Your GST payable is significantly different from previous quarters
• Revenue has changed substantially
• Large purchases were made during the reporting period
• New accounting software was recently implemented
• Multiple staff members handle bookkeeping

Unexpected variations often indicate potential coding or reporting errors.

How Cloud Accounting Software Helps Reduce GST Mistakes

Modern bookkeeping systems such as:

• Xero
• MYOB
• QuickBooks Online

can help automate:

• GST calculations
• Invoice tracking
• Bank reconciliation
• Financial reporting

While automation reduces manual errors, regular reviews remain essential to ensure data accuracy.

Also Check: When Is BAS Due in 2026? Important ATO Deadlines for Perth Businesses

Benefits of Working With a Professional Bookkeeper

A qualified bookkeeper can identify GST issues before they become costly problems.

Professional bookkeeping support can assist with:

• GST coding reviews
• BAS preparation
• Transaction reconciliation
• Payroll compliance
• Financial reporting
• ATO record-keeping requirements

Many Perth business owners find that professional support saves significant time while improving compliance and financial visibility.

GST Compliance Trends Businesses Should Watch

The ATO continues to increase its use of digital reporting and data matching technologies.

Businesses should expect greater focus on:

• Accurate GST claims
• Electronic record keeping
• Timely BAS lodgements
• Transaction transparency

Maintaining strong bookkeeping practices today can help reduce future compliance risks and support smoother interactions with the ATO.

Why Choose JGW Bookkeeping Services?

At JGW Bookkeeping Services, we help Perth businesses improve bookkeeping accuracy and reduce GST-related stress.

Our services include:

• BAS preparation and lodgement
• GST reporting support
• Bank reconciliations
• Payroll processing
• Financial reporting
• Ongoing bookkeeping management

We work with businesses across a wide range of industries, helping owners stay compliant while focusing on growth.

Final Thoughts

Reducing GST mistakes before lodging your BAS is one of the simplest ways to avoid ATO issues, improve financial accuracy, and maintain confidence in your business records.

By keeping organised records, reviewing transactions regularly, and seeking professional bookkeeping support when needed, Perth businesses can significantly reduce BAS errors and stay on top of their tax obligations.

If you need assistance with GST reporting, BAS preparation, or ongoing bookkeeping support, JGW Bookkeeping Services can help keep your business compliant and financially organised year-round.

FAQs

What is the most common GST mistake businesses make?

Incorrect GST coding of expenses and claiming GST on purchases that are GST-free are among the most common mistakes.

Can accounting software completely eliminate GST errors?

No. While software automates many processes, transaction reviews and accurate data entry are still essential.

Do I need a tax invoice to claim GST credits?

Generally, yes. For purchases over A$82.50 (including GST), a valid tax invoice is usually required to claim GST credits.

What should I do if I discover a GST error after lodging BAS?

Depending on the size of the error, you may be able to correct it in a future BAS or need to lodge an amendment. Professional advice can help determine the correct approach.

Can a bookkeeper lodge BAS on my behalf?

Yes. Registered BAS agents can prepare and lodge BAS for eligible businesses while helping ensure compliance with ATO requirements.