The 31st hour: when a junior's roster starts costing you super

A 17-year-old casual on your Level 1 rate earns $19.83 an hour. Roster them 30 hours and the week costs you $594.90. Roster them 31 and the same week costs $688.50. That single extra hour cost you $93.60, which is 4.7 times the rate you wrote next to their name.

Nothing went wrong in payroll. Super for an employee under 18 is decided by hours, not dollars. Work them 30 hours or less in a week and you owe no super guarantee at all. Work them more than 30 and the 12% lands on the whole week's earnings, not just the hour that tipped it over. It is a rostering decision that only ever shows up in the pay run, which is exactly the wrong order.

The short version: an employee under 18 is entitled to super guarantee only if they work more than 30 hours in a week for you, regardless of how much you pay them. The test is per employer, and the ATO says you cannot average the hours across a fortnightly or monthly pay period. Cross 30 and the 12% applies to that week's qualifying earnings in full. On their 18th birthday the hours test disappears and super is owed on everything. This is general information, not financial or legal advice.

The rule, and the three bits venues get wrong

The ATO puts it in one sentence: employees under 18 are eligible for super guarantee "if they work for you for more than 30 hours in a week, regardless of how much you pay them". There is no dollar threshold left anywhere in this, so hours are the only variable. The mechanism sits in section 28 of the Superannuation Guarantee (Administration) Act 1992, which takes a young part-time worker's wages out of the super calculation entirely rather than discounting them.

• It is per employer, not per person. The ATO's own worked example is a 17 year old with two jobs: 32 hours in one week at a hardware shop, 6 hours a month at a cafe. The shop pays super for that week. The cafe pays none, ever. Your 28-hour junior could be doing 45 hours across three venues and not one of you owes a cent.
• It is the whole week, not the hours above 30. The 31st hour does not attract 12% on its own. It removes the exemption for that entire week, so the 12% applies to everything they earned in it, loading and penalties included.
• It is under 18, not under 21. Junior percentages in the Hospitality Award run all the way to 20 years old. The super exemption stops dead on the 18th birthday, so an 18 year old on 70% of the adult rate still gets super on every hour they work.

What the 31st hour actually costs

Under MA000009, a junior is paid a percentage of the adult rate for their classification: 50% under 17, 60% at 17, 70% at 18, 85% at 19 and 100% at 20. Casuals add the 25% loading on top. Here is the same week at four common junior rates, using the adult minimums that applied from the first full pay period on or after 1 July 2026, on ordinary weekday hours with no penalties in play.

Those casual rates are our own calculation: the award's adult hourly minimum, times the junior percentage in clause 18.4, plus the 25% casual loading. Check yours against the Fair Work Ombudsman's Pay and Conditions Tool before you price anything off them, and confirm the classification level first, because the percentage is applied to whatever level you have them on.

Look down the last column and the ratio never moves. Thirty-one hours at 112% of the wage is 34.72 hours of pay, against 30 hours of pay the week before. The difference is always 4.72 hours of wages, whatever the rate and whatever the age.

The 31st hour always costs 4.72 hours of pay. The 32nd costs 1.12.

Which makes 31 the worst number on the roster

The cliff is a one-off. Once the week has lost its exemption, every further hour costs the wage plus 12% and nothing more. Same 17 year old, same $19.83, across a full week.

So the expensive roster is not the big one, it is the one that pokes a single hour over the line. If a junior genuinely needs 31 hours, they may as well have 36, because you have already paid for the crossing. If they only need 31 because someone stayed back on Thursday, that hour would have been $22.21 cheaper on almost anyone else's timesheet. Casuals also hit overtime rates above 38 hours a week under clause 11.2, and overtime generally is not qualifying earnings, so the maths above only holds up to that point.

A fortnightly pay run will hide this from you

This is where the payroll software advice goes wrong, and it is worth being blunt about. The ATO's position, citing Superannuation Guarantee Determination SGD 93/1, is that the count is "the actual number of hours the employee works in that week" and that "you can't average the hours across fortnightly or monthly pay periods". A system that divides a fortnight by two will read 59 hours as 29.5 a week and quietly owe nothing.

SGD 93/1 also settles the other half of it: hours worked means hours actually worked, not hours agreed. Its own example is an employee with a written agreement for 25 hours a week who picks up 10 extra in the school holidays, and for those weeks the agreement counts for nothing. Your timesheet decides this, not your roster. A 29-hour roster plus two stay-backs and a covered break is a 31-hour week, and you will not know until it has already happened.

How to see the cliff before the pay run

1. Flag every staff member under 18 with their date of birth in the roster, not just in payroll. The exemption ends on a birthday, and nobody remembers that a week out.
2. Set your own soft cap at 28 rostered hours for those staff. Two hours of headroom absorbs the stay-backs and the extra half shift without a decision being made for you.
3. Count the week the same way every time. Use one consistent roster week per person and stick to it, and check with the ATO if your roster week and your pay week do not line up.
4. Check timesheets against the 30-hour line before you approve them, not after. This is the only step that actually catches it, because the roster never had the real number in it.
5. If someone will cross, decide it on purpose. Either give them the hours properly, at 34 or 36, or move the one loose hour to someone who is 18 or over, or already past 30. Do not let a shift swap make the call.
6. Keep the state rules separate. Child employment laws set their own limits on how long and how late under-18s can work, and they have nothing to do with the super test.

One thing that has changed the feel of all this: since 1 July 2026, super has to reach the fund within 7 business days of payday rather than 28 days after the end of a quarter. The cost was always there. Now it leaves your account in the same week as the shift did, and your staff can see it land.

The exemption may not survive the year

On 31 August 2026 the Super Members Council published modelling putting the cost of this exemption at $411 million a year in unpaid super nationally, $115 million of it in Victoria and $105 million in New South Wales, with about 156,000 Victorian teenagers missing an average of $735 in 2026-27. Its analysis found 91% of under-18s work fewer than 30 hours a week, which is the whole point: the exemption is not an edge case, it is the norm.

The Greens have introduced an amendment bill and secured a Senate inquiry due to report in November 2026, and Labor's national conference voted to extend compulsory super to all under-18s. Treasurer Jim Chalmers has called reform important but has not legislated. Nothing has changed yet, so the 30-hour test is still the law today. It is a fair bet that a roster built around dodging it has a short shelf life.

Where Shiftly fits

The cliff is invisible for one boring reason: the number that triggers it lives in the roster, and the cost appears in the pay run, and for most venues those are two different screens a fortnight apart. Shiftly is free workforce management for Australian venues, rostering plus award-aware timesheets, so you can see a junior's weekly hours adding up while you are still building the week and check what a shift should cost before you approve it. It is a calculation tool and a facilitator, not a payroll provider, and it does not make anyone compliant on its own. The other half is the reason juniors get pushed over 30 in the first place: at 4pm you have one loose hour and one person who might say yes. Shiftly is the roster that fills itself, with an on-demand staffing network built into the same roster, so that hour can go to someone nearby who sees the venue, the time and the pay before they accept, instead of onto the timesheet of the one person it costs 4.7 times as much on. Get started with Shiftly.

Frequently asked questions

Do I have to pay super for a 16 year old?

Only for a week in which they work more than 30 hours for you. The ATO's rule is that employees under 18 are eligible for super guarantee if they work more than 30 hours in a week, regardless of how much you pay them, so a 16 year old on 20 hours a week gets no super no matter how many weeks they do it. There is no minimum earnings threshold, only the hours test, and it applies the same way to casual, part-time and full-time juniors.

Is the super calculated on the hours over 30 or on the whole week?

The whole week. The exemption works by taking the wages out of the calculation entirely for a young worker employed 30 hours or less, so once they work more than 30 the exemption is gone for that week and the 12% applies to all of that week's qualifying earnings, casual loading and penalty rates included. That is why one extra hour costs 4.72 hours of pay rather than 1.12.

My junior does 40 hours a week across three venues. Who owes the super?

Nobody, if none of you individually gives them more than 30 hours in that week. The 30-hour test is applied per employer, and the ATO's published example makes exactly this point using a 17 year old with a hardware job and a cafe job. It is one of the reasons the Super Members Council calls the rule outdated, given how normal it is for a hospitality junior to hold two or three casual jobs at once.

Do junior rates change how much super I pay per hour?

Yes, because the 12% sits on their actual earnings, and a 17 year old in hospitality is on 60% of the adult rate for their level. A 20 year old is already on 100% under MA000009, and the December 2026 junior rates decision does not touch hospitality at all. So the super line moves with age twice over: the percentage climbs, and at 18 the 30-hour exemption disappears completely.