How the Denmark selvstændig calculator is verified

Inputs

Input	Field	Type
Annual surplus (DKK)	`annualSurplus`	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)
AM-bidrag (8%)	`amBidrag`	`$round(annualSurplus * $const.amRate, 2)`
After Am Bidrag	`afterAmBidrag`	`$round(annualSurplus - amBidrag, 2)`
Bottom + municipal + health tax	`baseTax`	`$round($const.baseRate * $max([0, afterAmBidrag - $const.personalAllowance]), 2)`
Intermediate / top / top-top tax	`bracketTax`	`($a := afterAmBidrag; $round($const.mellemRate * $max([0, $min([$a, $const.topStart]) - $const.mellemStart]) + $const.topRate * $max([0, $min([$a, $const.topTopStart]) - $const.topStart]) + $const.topTopRate * $max([0, $a - $const.topTopStart]), 2))`
Net income / year	`netIncome`	`$round($max([0, annualSurplus - amBidrag - baseTax - bracketTax]), 2)`

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
`amRate`	0.08
`personalAllowance`	54100
`baseRate`	0.34
`mellemStart`	641200
`topStart`	777900
`topTopStart`	2592700
`mellemRate`	0.075
`topRate`	0.075
`topTopRate`	0.05

Test vectors (3)

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 — 600,000 DKK surplus — a typical full-time freelancer

given `annualSurplus`	600000
expect `amBidrag`	48000
expect `afterAmBidrag`	552000
expect `baseTax`	169286
expect `bracketTax`	0
expect `netIncome`	382714

Case 2 — 250,000 DKK — part-time

given `annualSurplus`	250000
expect `amBidrag`	20000
expect `afterAmBidrag`	230000
expect `baseTax`	59806
expect `bracketTax`	0
expect `netIncome`	170194

Case 3 — 1,200,000 DKK — into the top bracket

given `annualSurplus`	1200000
expect `amBidrag`	96000
expect `afterAmBidrag`	1104000
expect `baseTax`	356966
expect `bracketTax`	34710
expect `netIncome`	712324

Sources

Skattestyrelsen — AM-bidrag (labour market contribution) · checked 2026-08-22
Nye skattegrænser 2026: mellemskat, topskat og top-topskat · checked 2026-08-22

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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