How the interstate wage threshold actually gets calculated

Every state publishes a payroll tax threshold as if it were the only state you employ in. The moment you pay wages in a second state, that assumption breaks — and the threshold you actually get is calculated, not looked up. Here’s the exact mechanics, using Revenue NSW’s own published worked example, followed by an extended three-state example to show how it scales.

The formula

Threshold available in a state = full threshold × (wages paid in that state ÷ total Australian wages)

The logic: the full threshold assumes 100% of your wages are paid in that one state. If only a fraction of your total Australian wages are actually paid there, you only get that same fraction of the threshold. This applies directly to NSW and, with an additional phase-out layer, to VIC. QLD works on a related but structurally different principle, covered further down.

Worked example — apportionment

Revenue NSW publishes this exact scenario: a business pays $900,000 in NSW wages, and a combined $2,100,000 in QLD and VIC wages, for total Australian wages of $3,000,000.

NSW threshold available = $1,200,000 × ($900,000 ÷ $3,000,000)
= $1,200,000 × 30%
= $360,000

Taxable NSW wages = $900,000 − $360,000 = $540,000
Estimated NSW liability = $540,000 × 5.45% = $29,430

NSW’s wage share of the business’s total Australian wages is 30% — so the business gets 30% of the full NSW threshold, not the full amount. This is why comparing a multi-state wage bill against a single state’s published threshold, without apportioning it first, consistently overstates the tax-free amount you actually have.

Worked example — a genuine three-state split

The two-state Revenue NSW example is the clearest illustration of the principle, but most businesses using this site’s comparison tool are paying wages in all three modelled states at once, not just NSW plus a combined “everyone else” figure. Take a hypothetical business paying $700,000 in NSW, $500,000 in VIC and $400,000 in QLD, for total Australian wages of $1,600,000, for the full financial year. Run through this site’s actual tested calculation functions, the results come out structurally different from each other even though the wage figures are the same order of magnitude:

• NSW — wage share 43.8%, threshold available $525,000, taxable wages $175,000, estimated liability $9,537.5.
• VIC — wage share 31.3%, threshold available $312,500, taxable wages $187,500, estimated liability $9,093.75.
• QLD — deduction available $1,257,142.86 (calculated from total Australian wages, not QLD’s wage share), taxable wages $0, estimated liability $0.

Notice that QLD’s deduction isn’t simply $1,300,000 scaled down by QLD’s share of total wages the way NSW’s and VIC’s thresholds are — it’s calculated from total Australian wages first (in this example, still under QLD’s deduction-threshold trigger point, so the full maximum applies before being subtracted from QLD wages specifically). That structural difference is exactly why running a three-state estimate by hand, using one state’s formula as a mental template for the others, produces a plausible-looking but wrong number for at least one of the three.

Worked example — why wages in unmodelled states still matter

“Total Australian wages” in the formula above means exactly that — every dollar of wages paid anywhere in Australia, not just in the states this site calculates a liability for. Take a business paying $900,000 in NSW wages and nothing else. Run alone, its apportioned NSW threshold is the full $1,200,000 and its taxable wages are $0, giving an estimated NSW liability of $0. Now add $300,000 in wages paid in, say, Western Australia — a state this site doesn’t calculate a separate liability for. That WA wage figure still counts toward total Australian wages, which shrinks the NSW threshold to $900,000 and pushes taxable NSW wages up to $0 — an estimated NSW liability of $0, noticeably higher than the NSW-only figure, purely because of wages paid in a state that never appears in this site’s own results. This is precisely why the comparison calculator asks for an “elsewhere in Australia” figure even though it can’t show you a QLD- or VIC-style breakdown for it — leaving that field blank when it shouldn’t be zero is one of the most common ways an estimate comes in artificially low. See our guide to what counts as wages for what should be included in that figure.

Worked example — part-year employers

If you didn’t employ for the full financial year, a second proration applies on top, based on days employed. Revenue NSW’s published example: a business with $1,500,000 in NSW wages, employed for 184 of the 365 days in the financial year.

Threshold = $1,200,000 × (184 ÷ 365) = $604,931.51
Taxable wages = $1,500,000 − $604,931.51 = $895,068.49

If a business pays wages in more than one state and employs for only part of the year, both calculations apply together — apportion by wage share first, then prorate the result by days employed. Doing it in the other order, or applying only one, produces a number that looks plausible but is wrong.

Common mistakes business owners make here

• Forgetting that unmodelled-state wages still count. Wages paid in WA, SA, TAS, ACT or NT aren’t calculated separately by this site, but they still count toward total Australian wages — and therefore still reduce the threshold available in NSW, VIC and QLD.
• Applying NSW’s apportionment logic to QLD. QLD’s deduction isn’t apportioned by QLD’s wage share the way NSW’s and VIC’s thresholds are — it’s calculated from total Australian wages and applied directly. See our state-by-state comparison for the full contrast.
• Getting the order of operations wrong for part-year, multi-state employers. Apportion by wage share first, then prorate by days — reversing the order produces a different, incorrect number.
• Assuming the apportionment is a one-off calculation. It’s based on the current financial year’s actual wages — a business whose wage split shifts significantly from one year to the next needs to recalculate, not carry forward last year’s threshold.
• Forgetting grouping layers on top. If you’re grouped, the same apportionment formula runs on the group’s combined wages, not just your own entity’s — see how grouping affects your threshold.

Why this only shows up on a comparison tool

A state revenue office’s own calculator only knows about wages paid in that state — it has no visibility into what you paid elsewhere, so it can’t apply this formula for you even if it wanted to. That’s the specific gap this site fills: enter your full interstate wage split into the interstate apportionment calculator and it applies both steps in the right order automatically, for NSW, VIC and QLD, using the same calculation functions used to compute the worked examples in this post.

What to do next

1. Gather your full-year wage figures per state, including an “elsewhere” total for WA, SA, TAS, ACT and NT — all of it feeds the total Australian wages figure.
2. Run the figures through the interstate calculator rather than applying one state’s formula to another by hand.
3. If you’re grouped or employed for only part of the year, layer those factors in — both change the result materially and interact with the apportionment in a specific order.
4. Recalculate each financial year, since the apportionment tracks your actual current-year wage split.