Rules Around Multiple Jobs and Tax in Australia — Why Workers Get Caught Out

The single rule that catches workers out

The rule is published clearly on the ATO’s multiple jobs or payments page: the tax-free threshold can only be claimed on one job at a time. The ATO’s standard guidance is to claim it on the highest-paying job. The TFN declaration form has a specific question — “Do you want to claim the tax-free threshold from this payer?” — and the answer should be Yes for the highest-paying job and No for all others.

The reason this matters: if a worker claims the threshold on both jobs, both employers withhold tax as if their job were the only source of income. Both apply the tax-free amount to the income they’re paying. The combined withholding is well below what’s actually owed once total income is reconciled, and the difference is the year-end bill.

The fix is straightforward — only claim the threshold once. The catch is that workers who didn’t know the rule, or set up the threshold on the wrong job, can carry the under-withholding for months before realising.

The tax-free threshold and why it can only sit on one job

The tax-free threshold is a single allowance applied to total annual income, not to each job separately. The ATO’s tax-free threshold page sets out the current amount.

From the ATO’s perspective, the entire threshold gets applied once across all income sources. From the employer’s perspective, each one is separately calculating PAYG withholding for the income they pay. So claiming the threshold on multiple jobs essentially “claims” the same allowance multiple times in withholding, which can’t actually happen at reconciliation.

The mechanics:

• Job 1 (claim threshold): pays first portion of income tax-free, then taxes the next portion at lower rates
• Job 2 (no threshold): should withhold tax from the first dollar at the standard rate
• Year-end: total income gets taxed once with one threshold, and the combined withholding either matches, exceeds, or falls short of the actual liability

When both jobs claim the threshold, Job 2 withholds far less than it should. The shortfall accumulates through the year and becomes the year-end bill.

How combined income pushes brackets up

Even with the threshold correctly claimed on only the highest-paying job, multiple jobs commonly produce a year-end shortfall for a different reason: bracket interaction. Each employer’s withholding calculation assumes their income is the only income — so each calculates within the brackets that would apply if the worker only earned what that one employer pays.

Combined, the worker’s total income often crosses into higher brackets than any single employer is withholding for. The withholding tables don’t know about the second job, so they can’t account for it. The ATO reconciles at lodgment by applying the actual progressive rates to the combined income — and the gap between what should have been withheld and what was actually withheld becomes the bill.

This is particularly common when:

• Both jobs pay in a similar bracket range, but combined push into a higher bracket
• One job is occasional or seasonal and the other is steady
• Both jobs are part-time, but together exceed the full-time threshold for higher brackets

Why year-end produces a bill instead of a refund

The tax return at year-end is a reconciliation. Total income is calculated. Total tax owing is calculated using the progressive rates. Total tax withheld through the year is subtracted. If the withheld amount is greater than owing, refund. If less, bill.

Multiple-job workers commonly land in bill territory because of:

• The threshold being incorrectly claimed twice (worst case)
• Combined income crossing into higher brackets than either employer was withholding for
• The Medicare Levy being correctly withheld on each job but not enough on the combined income
• The HELP repayment trigger (if applicable) being missed because each employer didn’t see the combined income

For the first three, the ATO’s processes catch them at lodgment. For the HELP issue specifically, our HECS-HELP article covers how the repayment process is structured — and it’s vulnerable to the same multiple-jobs gap.

Fixing the withholding through the year

Workers who realise they’re heading toward a year-end shortfall — or who want to avoid it — can adjust withholding mid-year through any employer. The mechanism is the Withholding Declaration:

• Complete a Withholding Declaration with the relevant employer
• Specify additional tax to be withheld each pay period
• The employer adds that amount to the standard PAYG withholding
• The extra withholding shows up at lodgment as additional credit, reducing the bill (or producing a refund)

The ATO has tax withheld calculators that help work out the right amount. The TFN declaration and Withholding Declaration forms are on the ATO’s forms hub.

For workers who’d rather not adjust withholding and instead set aside savings to cover the bill, the practical move is to estimate the gap (using the ATO’s tax estimator) and put that amount into a separate account each pay. Either approach works; both avoid the bill-shock.

Beyond two PAYG jobs — gig, contract, and side income

The multiple-jobs problem isn’t limited to two PAYG employees. The same dynamic affects:

• Workers with one PAYG job and side income from gig work, freelancing, or contracting (where no PAYG is withheld at all)
• Workers with multiple casual jobs across different employers
• Workers with one PAYG job and rental property income
• Workers receiving taxable Centrelink payments alongside employment

In all these cases, the ATO’s working as an employee section covers the relevant rules. The general principle stays the same: the more income sources without combined-aware withholding, the higher the chance of a year-end shortfall.

For workers with significant non-PAYG income, the ATO’s PAYG instalments system (a quarterly pre-payment of expected tax) is sometimes the cleanest way to spread the obligation across the year. For most workers with simple multi-job patterns, a Withholding Declaration on one of the jobs is enough.

Frequently asked questions

Should I claim the tax-free threshold on multiple jobs?

No. The tax-free threshold can only be claimed on one job at a time, and the ATO recommends claiming it on the highest-paying job. Claiming it on multiple jobs leads to under-withholding and a tax bill at year-end. The same rule applies to people with multiple sources of regular income from different employers.

Why do I owe tax at year-end with two jobs?

Each employer withholds tax based on the income from that job alone. Combined income often pushes the worker into a higher tax bracket than any single employer is withholding for, producing a shortfall at year-end. The shortfall is normal — the ATO designed the system to reconcile at the return — but it surprises workers expecting a refund.

Can I have my second-job employer withhold extra tax?

Yes. Employees with multiple jobs can ask any employer to withhold additional tax voluntarily, by completing a Withholding Declaration with the request. This avoids the year-end bill at the cost of a smaller weekly net pay. The ATO publishes calculation tools for working out the right additional amount.

The single thing to do if you’ve just started a second job

The single most useful thing any worker who has just started a second job can do is check their TFN declarations on both jobs. The threshold should be claimed on the highest-paying one and not on any other. If the wrong job has it, file a new TFN declaration with each employer to correct it — the change is free, takes about ten minutes, and prevents months of accumulating under-withholding.

For workers who are already several months in with the threshold incorrectly claimed twice, the most practical step is to use the ATO’s tax estimator to project the year-end shortfall, then set aside that amount or use a Withholding Declaration to recover some of the gap before lodgment. The bill will still come — but it won’t be a surprise.