Do You Pay More Tax on a Second Job in Australia?

Your Tax Rate Is Based on Total Income, Not Per Job

The core misunderstanding is thinking a second job gets taxed at a different, higher rate purely because it's your second source of income. It doesn't. The ATO looks at your combined income from all sources for the year and applies the individual marginal tax rates to that total, exactly as it would if all the income came from one job.

What actually differs between jobs is how much tax is withheld from each pay throughout the year, which is a cash flow and estimation issue, not a difference in the actual tax rate that ultimately applies.

The Tax-Free Threshold, and Why You Can Only Claim It Once

Every Australian resident gets the first $18,200 of annual income tax-free. When you start a job, you complete a Tax File Number declaration and tick a box to claim the tax-free threshold with that employer, which tells them to withhold tax as if that $18,200 is coming through this job.

You're only meant to claim the threshold with one employer at a time, ideally your highest-paying job. If you claim it on both, both employers under-withhold relative to what your combined income will actually owe, and you're likely to face a tax bill when you lodge.

Why the Second Job's Withholding Looks So High

Without the tax-free threshold claimed, your second employer withholds tax from the very first dollar you earn there, using a schedule built for someone with no tax-free threshold at all. That produces a noticeably bigger chunk taken out of each pay compared to your main job, even though the actual work and pay rate might be identical.

This isn't a penalty or an error, it's the system deliberately over-withholding on the second job so that, once your two incomes are combined and taxed together at year end, you're less likely to owe money. Often it results in a refund instead.

Where the Medicare Levy Fits In

The Medicare levy, generally 2% of taxable income, is calculated once on your combined income for the year, not separately per employer. Each employer withholds an estimate of it along with income tax, and it's reconciled at tax time against your actual total income. Higher earners without private hospital cover may also face the Medicare levy surcharge, again calculated on combined income.

A Worked Example

Say you earn $60,000 from your main job and pick up $15,000 from a second job, $75,000 combined. Your main employer withholds tax with the threshold applied, roughly in line with what $60,000 alone would owe. Your second employer withholds without the threshold, at a noticeably higher rate on that $15,000. Add both together across the year, and the total withheld tends to land close to, or slightly above, what $75,000 combined actually owes at the individual marginal rates, which is why a refund is common rather than a surprise bill, provided the threshold was only claimed once.

What to Check With Your Employer

• Your TFN declaration on each job, confirm the tax-free threshold box is only ticked on your primary employer
• Your total expected income for the year across all jobs, so you can estimate roughly where you'll land at tax time
• Whether extra withholding is worth requesting if you're consistently under-withheld, you can ask an employer to withhold an additional fixed amount each pay

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