Understanding Tax File Numbers (TFNs) for an account holder that is under 18 years old

Is a TFN required for a savings account held by a person who is under 18?

Under Australian taxation laws, we are authorised to collect a Tax File number (TFN), an Australian Business Number (ABN), or an exemption for interest-bearing accounts. While it’s not compulsory to provide a TFN, ABN or a TFN exemption, if you don’t, we may be required to withhold a portion of your interest earned on the account. The money we withhold is paid to the Australian Taxation Office (ATO).

What happens if a TFN or exemption isn’t linked to the savings account? 

If you don’t provide your TFN or an exemption, we’re required to deduct Withholding Tax at the highest tax rate, plus Medicare Levy on all accounts that don’t have a TFN or an exemption.

Are children subject to withholding tax if a TFN or TFN exemption isn’t provided? 

Yes. If a TFN or a TFN exemption is not provided, we’re required to withhold tax from any interest earned, even if the account holder is under 18. If you’ve previously linked an under 16 exemption to the account, we may still withhold tax if interest paid on the account exceeds certain thresholds.

What do I need to do if tax was withheld on a savings account?

If you provided a TFN or an exemption for the account and the withholding tax was deducted from the interest earned in the current financial year, you may be eligible to request a refund by visiting your local branch. For any tax withheld in previous financial years, you may claim these by lodging an income tax return with the Australian Tax Office (ATO).

What are the thresholds for ‘No TFN withholding tax’ on children’s accounts?

The thresholds for withholding tax depend on the account holder’s age during the calendar year the interest is paid, as well as how much interest is earned on the account and whether the under 16 exemption is applied.

These thresholds are set by the ATO per annum and pro-rated to how many days the interest is earned if the period is less than a year .  

For more information on threshold amounts, please refer to the ATO website.

Examples of how withholding tax is calculated.  

Here’s are some examples of how withholding tax is calculated. The threshold is pro-rated for a shorter period.  

Taxation considerations contained in this page are general in nature. You should refer to the ATO website or seek professional tax advice for specific guidance on your circumstances.

A child under 16 years old

• Less than $120 in interest earned per year → No tax withheld. 
• Between $120 and $420 in interest earned per year, and
  • TFN or date of birth is provided → No tax withheld
  • No TFN or date of birth is provided → Tax withheld at the highest tax rate
• More than $420 in interest per year:
  • TFN provided → No tax withheld
  • Date of birth is provided → Tax is withheld at the highest tax rate
  • TFN or date of birth is not provided → Tax withheld at the highest tax rate

A child over 16 years old

• Less than $120 in interest earned per year → No tax withheld.
• More than $120 in interest earned per year and
  • TFN provided → No tax withheld. 
  • TFN not provided → Tax withheld at the highest tax rate 

Joint accounts with an adult and a child under 16: 

• These follow the same rules as accounts held by over 16 year-olds. 

A child is considered under 16 until the end of the calendar year in which they turn 16. For example, if a child turns 16 in July 2025, they are treated as under 16 until 31 December 2025 (inclusive).

Can a person under 18 apply for a TFN?

Yes. There’s no minimum age to apply for a TFN.  You can apply for a TFN through Australia Post or Services Australia. Visit the ATO website for more information on how to apply for a TFN.

Whose TFN should be provided for an under 18 year old savings account?

You should refer to the Australian Tax Office (ATO) website or seek professional tax advice when deciding which TFN is most appropriate to provide.

How do I link a TFN to my child’s an  account?

You can add a TFN to an account using either the Westpac App or Online Banking. We don’t automatically apply TFNs from an existing account to any new account(s) created, so the account holder or parent/guardian must provide consent for a TFN to be added to any new account(s) created.

Here's how:

Through the Westpac App

Make sure you have the latest version of the app. 

1. Search Tax File Number
2. Select the account you wish to update
3. Tap Choose option
4. Enter a TFN, provide a TFN exemption or use an existing TFN
5. Enter details and tap Update

Via Online Banking

Log in to Westpac Online Banking: 

1. Go to Services > Preferences > Tax File Number
2. Select Update Tax File Number
3. If prompted, enter the SMS Code sent to your registered mobile and select Authorise
4. Select the account you wish to update
5. Enter a TFN, provide a TFN exemption or use an existing TFN