How the Türkiye yıllık ücretli i̇zin calculator is verified

Inputs

Input	Field	Type
Years of service with this employer	`serviceYears`	number
Your age	`age`	number
You work in underground work (yer altı işleri)	`worksUnderground`	boolean
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)
Band Days	`bandDays`	`($s := $n(serviceYears); $s < $const.qualifyingYears ? 0 : ($s <= $const.bandYears5 ? $const.bandDaysTo5Years : ($s < $const.bandYears15 ? $const.bandDaysTo15Years : $const.bandDaysFrom15Years)))`
Days Entitled	`daysEntitled`	`($s := $n(serviceYears); $s < $const.qualifyingYears ? 0 : ($base := bandDays + (worksUnderground = true ? $const.undergroundExtraDays : 0); $floored := ($n(age) <= $const.youngAgeThreshold or $n(age) >= $const.olderAgeThreshold) ? ($base > $const.ageFloorDays ? $base : $const.ageFloorDays) : $base; $floored))`
Days Remaining	`daysRemaining`	`($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
`qualifyingYears`	1
`bandDaysTo5Years`	14
`bandDaysTo15Years`	20
`bandDaysFrom15Years`	26
`bandYears5`	5
`bandYears15`	15
`ageFloorDays`	20
`youngAgeThreshold`	18
`olderAgeThreshold`	50
`undergroundExtraDays`	4

Test vectors (16)

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 under a year there is no statutory entitlement at all

given `serviceYears`	0
given `age`	35
given `worksUnderground`	no
given `daysTaken`	0
expect `bandDays`	0
expect `daysEntitled`	0

Case 2 — N2 at one year the first band opens at 14

given `serviceYears`	1
given `age`	35
given `worksUnderground`	no
given `daysTaken`	0
expect `bandDays`	14
expect `daysEntitled`	14

Case 3 — N3 five years is still band a, because the article includes five

given `serviceYears`	5
given `age`	35
given `worksUnderground`	no
given `daysTaken`	0
expect `daysEntitled`	14

Case 4 — N4 just over five years moves to 20

given `serviceYears`	6
given `age`	35
given `worksUnderground`	no
given `daysTaken`	0
expect `daysEntitled`	20

Case 5 — N5 fourteen years is still band b, because band c starts AT fifteen

given `serviceYears`	14
given `age`	35
given `worksUnderground`	no
given `daysTaken`	0
expect `daysEntitled`	20

Case 6 — N6 fifteen years reaches 26, and that is the top band

given `serviceYears`	15
given `age`	35
given `worksUnderground`	no
given `daysTaken`	0
expect `daysEntitled`	26

Case 7 — N7 a 17-year-old with two years' service gets the 20-day floor, not 14

given `serviceYears`	2
given `age`	17
given `worksUnderground`	no
given `daysTaken`	0
expect `bandDays`	14
expect `daysEntitled`	20

Case 8 — N8 so does a 55-year-old with two years' service — the floor is two-sided

given `serviceYears`	2
given `age`	55
given `worksUnderground`	no
given `daysTaken`	0
expect `daysEntitled`	20

Case 9 — N9 the young threshold is inclusive at 18, so 18 still floors to 20

given `serviceYears`	2
given `age`	18
given `worksUnderground`	no
given `daysTaken`	0
expect `daysEntitled`	20

Case 10 — N10 nineteen is above the young threshold and below 50, so back to the band

given `serviceYears`	2
given `age`	19
given `worksUnderground`	no
given `daysTaken`	0
expect `daysEntitled`	14

Case 11 — N11 the older threshold is inclusive at 50

given `serviceYears`	2
given `age`	50
given `worksUnderground`	no
given `daysTaken`	0
expect `daysEntitled`	20

Case 12 — N12 underground work adds four days to a band

given `serviceYears`	2
given `age`	35
given `worksUnderground`	yes
given `daysTaken`	0
expect `daysEntitled`	18

Case 13 — N13 the floor applies to the total, so an underground 55-year-old on band a sees 20

given `serviceYears`	2
given `age`	55
given `worksUnderground`	yes
given `daysTaken`	0
expect `daysEntitled`	20

Case 14 — N14 underground work earns nothing before the qualifying year either

given `serviceYears`	0
given `age`	55
given `worksUnderground`	yes
given `daysTaken`	0
expect `daysEntitled`	0

Case 15 — N15 days already taken come off the remainder

given `serviceYears`	6
given `age`	35
given `worksUnderground`	no
given `daysTaken`	8
expect `daysRemaining`	12

Case 16 — N16 taking more than the entitlement never goes negative

given `serviceYears`	2
given `age`	35
given `worksUnderground`	no
given `daysTaken`	40
expect `daysRemaining`	0

Sources

İş Kanunu (4857) madde 53 — mevzuat.gov.tr (the one-year qualifying period; bands of 14, 20 and 26 days; the 20-day floor for workers 18 and under and 50 and over; four extra days for underground work) · 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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