How the Australia annual leave calculator is verified

Inputs

Input	Field	Type
Days you work per week	`daysPerWeek`	number
You are classified as a shiftworker for the NES	`isShiftworker`	boolean
Months of service accrued	`monthsWorked`	number
Days already taken	`daysTaken`	number

The formula

Each derived value below is computed by the Valem engine from the expression shown, in this order. Nothing else runs — there is no hidden code path.

Derived value	Field	Formula (JSONata)
Weeks Entitled	`weeksEntitled`	`(isShiftworker = true ? $const.shiftworkerWeeks : $const.baseWeeks)`
Full Year Days	`fullYearDays`	`weeksEntitled * $n(daysPerWeek)`
Days Entitled	`daysEntitled`	`($m := $clampFloorCap($n(monthsWorked), 0, $const.monthsPerYear); $round(fullYearDays * $m / $const.monthsPerYear, 1))`
Days Remaining	`daysRemaining`	`($r := daysEntitled - $n(daysTaken); $r < 0 ? 0 : $round($r, 1))`

Rates and thresholds

The expressions above read these as $const. They are the figures the annual refresh replaces, so they live as data rather than being written into the formulas — which is what makes a year-on-year change a one-line diff instead of an edit to arithmetic.

Constant	Value
`baseWeeks`	4
`shiftworkerWeeks`	5
`monthsPerYear`	12

Test vectors (8)

Every case is executed against this model on each build, by the Java engine and independently by a JavaScript one. A mismatch of a single cent fails the build, so the page cannot ship advertising a figure the model no longer produces.

Case 1 — N1 four weeks on a five-day week is 20 days

given `daysPerWeek`	5
given `isShiftworker`	no
given `monthsWorked`	12
given `daysTaken`	0
expect `weeksEntitled`	4
expect `daysEntitled`	20

Case 2 — N2 a shiftworker gets five weeks, so 25

given `daysPerWeek`	5
given `isShiftworker`	yes
given `monthsWorked`	12
given `daysTaken`	0
expect `weeksEntitled`	5
expect `daysEntitled`	25

Case 3 — N3 it accumulates, so half a year is half the leave — not nothing

given `daysPerWeek`	5
given `isShiftworker`	no
given `monthsWorked`	6
given `daysTaken`	0
expect `daysEntitled`	10

Case 4 — N4 a four-day week gets 16 over a full year

given `daysPerWeek`	4
given `isShiftworker`	no
given `monthsWorked`	12
given `daysTaken`	0
expect `daysEntitled`	16

Case 5 — N5 a six-day shiftworker week reaches 30

given `daysPerWeek`	6
given `isShiftworker`	yes
given `monthsWorked`	12
given `daysTaken`	0
expect `daysEntitled`	30

Case 6 — N6 no service accrued earns nothing

given `daysPerWeek`	5
given `isShiftworker`	no
given `monthsWorked`	0
given `daysTaken`	0
expect `daysEntitled`	0

Case 7 — N7 days already taken come off the remainder

given `daysPerWeek`	5
given `isShiftworker`	no
given `monthsWorked`	12
given `daysTaken`	8
expect `daysRemaining`	12

Case 8 — N8 taking more than the entitlement never goes negative

given `daysPerWeek`	5
given `isShiftworker`	no
given `monthsWorked`	12
given `daysTaken`	40
expect `daysRemaining`	0

Sources

Fair Work Ombudsman, Annual leave and the National Employment Standards — fairwork.gov.au (four weeks for each year of service; five weeks for a shiftworker) · checked 2026-10-11

Check it yourself — and reuse it

The whole model as JSON — inputs, outputs, formulas, vectors and sources in one re-runnable document.

This model is published under CC BY 4.0: use it, adapt it, build on it, with attribution. The licence covers the model — the expression of each rule and the arrangement of the catalog. The rates and thresholds are law, and nobody licenses those; the sources above are where they come from.

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