As you prepare your BAS, it is important to review your expenses carefully to ensure GST credits are claimed correctly.
Mixed business and private expenses
If you purchase goods or services that are used partly for business and partly for private purposes, you cannot claim the full GST amount. You are only entitled to claim the business portion of the GST.
Common examples include:
- Motor vehicle expenses
- Mobile phone and internet plans
- Home office running costs
- Computers or equipment used both at work and privately
What the ATO expects
The ATO expects businesses to:
- Apportion expenses on a fair and reasonable basis
- Keep records that support how the business percentage was calculated
- Only claim GST credits to the extent the expense relates to carrying on the business
Claiming 100 percent of the GST where there is private use is a common error and a regular focus area in ATO reviews.
Practical tips
To reduce the risk of errors:
- Review high-value and recurring expenses before lodging
- Use usage records, logbooks, or reasonable estimates to support apportionment
- Check that tax invoices meet GST requirements before claiming credits
Need help?
If you are unsure how to apportion GST or whether an expense is fully claimable, speak with your tax agent before lodging your BAS. Correcting mistakes early helps avoid amendments, penalties, and unnecessary ATO follow-up.
Claiming GST credits | Australian Taxation Office
Date published 02 Mar 2026 | Last updated 02 Mar 2026
