If you are working two jobs in Australia, you are making a smart move to boost your income. However, holding multiple jobs at the same time comes with a hidden financial trap.

Every year, thousands of Australians receive an unexpected tax bill from the Australian Taxation Office (ATO). The culprit? A simple, common error known as the working two jobs tax-free threshold mistake.

When you start a new job, your employer will hand you a Tax File Number (TFN) declaration form. How you fill out this form determines exactly how much tax is taken out of your regular pay.

Here is exactly how to fill out your TFN declaration when juggling two jobs so you keep your cash flow smooth and avoid a nasty surprise at tax time.

The Golden Rule: Only Claim the Tax-Free Threshold Once

In Australia, the tax-free threshold allows residents to earn up to $18,200 each financial year completely tax-free.

When filling out a TFN declaration, Question 9 (or Question 8 on newer digital versions via myGov) will ask: “Do you want to claim the tax-free threshold from this payer?”

If you have two jobs, your choices should look like this:

• Job 1 (Primary / Highest Paying): Tick YES.
• Job 2 (Secondary / Lower Paying): Tick NO.

Why this matters: If you tick “YES” on both forms, both employers will assume you earn your first $18,200 with them tax-free. They will both under-withhold your tax. At the end of the year, the ATO pools your combined income together, realizes you claimed a double exemption, and sends you a bill to pay back the shortfall.

Step-by-Step: Filling Out Your TFN Declarations

Follow this exact workflow to set up your payroll documents correctly.

1.Identify your primary income earner:

Step 1.

Look at your two positions. Your primary job should be the one that pays the highest salary, offers the most stable hourly schedule, or provides your consistent core weekly income.

2.Fill out Job 1’s TFN declaration:

Step 2.

On your primary job’s form, navigate to the question regarding the tax-free threshold and tick YES. Your payroll system will now process your pay using standard, lower-taxed progressive tax brackets.

3.Fill out Job 2’s TFN declaration:

Step 3.

On your second, lower-paying job’s form, tick NO to the tax-free threshold. This signals their payroll software to withhold tax from the very first dollar you earn at a higher, flat rate, covering your tax liabilities across your total combined earnings.

4.Cross-verify your first payslips:

Step 4.

Once both jobs pay you, review your payslips. Your primary job should show minor or no tax on very small amounts, while your second job should show a significantly higher percentage of tax withheld relative to its gross earnings.

What if Your Total Combined Income is Under $18,200?

There is one major exception to the rule. If you are working two very small part-time or casual jobs, and you are 100% certain that your total combined income from both jobs will be less than $18,200 for the entire financial year, you can safely tick YES for both employers.

Because your total earnings sit completely inside the tax-free bracket, no tax needs to be withheld.

Warning: If your situation changes and a sudden pay rise or extra hours push your total income over $18,200, you must immediately submit an updated Withholding Declaration form to your secondary employer changing your answer to NO.

Other Traps Facing Multi-Job Earners

Even if you fill out your TFN declarations perfectly, working multiple jobs can still cause minor tax discrepancies due to how your combined income interacts with other thresholds. Keep an eye out for these two elements:

1. HELP / HECS Student Loan Debts

If you have a student loan, your employers calculate your loan repayments based only on what you earn at that specific job. However, the ATO calculates your compulsory repayment on your combined total income. If your combined income pushes you into a higher repayment bracket, you might still owe money at the end of the year.

• The Fix: You can request your main employer to withhold additional voluntary tax amounts to cover your HECS gap.

2. The Medicare Levy

The 2% Medicare Levy applies across your total income once you cross specific thresholds. Much like HECS, individual payroll setups might not factor in your total combined earnings, causing a slight under-collection of the levy during the year.

Already Made the Mistake? How to Fix It Right Now

If you realize you have been claiming the tax-free threshold at both jobs, do not panic. It is an incredibly easy fix:

1. Log into your myGov account linked to the ATO.
2. Navigate to Employment > New employment to fill out an updated digital Withholding Declaration.
3. Alternatively, ask your second employer’s payroll team for a paper Withholding Declaration form.
4. Fill it out, tick NO to the tax-free threshold, and return it to them.

Your second employer will immediately adjust your pay cycle to withhold the correct amount of tax for the remainder of the financial year, mitigating or totally eliminating your potential end-of-year tax debt.