KAMMAREN Documentation

Quick start

Three ways to use KAMMAREN. Pick one.

1 — Fetch constants

curl https://kammaren.nu/api/constants/2026

Returns every Swedish tax constant for income year 2026 — PBB, IBB, AG rates, corporate tax, 3:12 rules, VAT rates, income tax brackets. Every value traced to a specific law paragraph. 290 municipal tax rates included separately.

2 — Verify a calculation

curl -X POST https://kammaren.nu/api/verify \
  -H "Content-Type: application/json" \
  -d '{
    "skill": "ag-avgifter",
    "input": {
      "gross_salary": 500000,
      "birth_year": 1990,
      "first_employee": false,
      "num_employees": 0
    },
    "expected": { "total_ag_avgift": 157100 }
  }'

3 — Run a calculation

Same endpoint, omit expected:

curl -X POST https://kammaren.nu/api/verify \
  -H "Content-Type: application/json" \
  -d '{
    "skill": "ag-avgifter",
    "input": {
      "gross_salary": 500000,
      "birth_year": 1990,
      "first_employee": false,
      "num_employees": 0
    }
  }'

Source of Truth API

All Swedish tax constants for a given income year. One URL. One JSON. Every value with a legal reference.

Endpoints

What's inside /api/constants/2026

55 constants total. 22 sections. Internal checksums verify that components sum correctly (e.g. 7 AG sub-rates = 31.42%).

basbelopp
  prisbasbelopp .............. 59 200 kr  (SFS 2025:XX, SCB)
  forhoijt_prisbasbelopp ..... 60 500 kr
  inkomstbasbelopp ........... 83 400 kr  (Pensionsmyndigheten)
  ibb_for_312 ............... 80 600 kr  (IL 57 kap 4 §, IBB 2025)

arbetsgivaravgifter
  total ...................... 31.42%     (SFL 2 kap 26 §)
  sjukforsakring ............. 3.55%
  foraldraforsakring ......... 2.00%
  alderspension .............. 10.21%
  efterlevandepension ........ 0.30%
  arbetsmarknad .............. 2.64%
  arbetsskada ................ 0.10%
  allman_loneavgift .......... 12.62%
  aldersreduktion ............ 10.21%    (67+ år, SFL 2 kap 27 §)
  vaxa_stodet ................ 10.21%    (max 35k/mån, SFL 2 kap 31 §)

moms
  standard ................... 25%       (ML 7:1)
  reducerad_1 ................ 12%
  reducerad_2 ................ 6%
  momsfri_grans .............. 120 000 kr (ML 9d kap)

bolagsskatt
  skattesats ................. 20.6%     (IL 65 kap 10 §)
  periodiseringsfond_max ..... 25%       (IL 30 kap 5 §)
  max_antal_fonder ........... 6         (IL 30 kap 7 §)

inkomstskatt
  skiktgrans ................. 643 000 kr (IL 65 kap 5 §)
  brytpunkt .................. 660 400 kr
  statlig_skatt .............. 20%

treslagregeln_312
  grundbelopp ................ 4 × IBB   (IL 57 kap 11 §, Prop. 2025/26:1)
  lonesparr .................. 8 × IBB   (IL 57 kap 16 §)
  lonebaserat_andel .......... 50%
  kapitalbaserat ............. SLR + 9%  (IL 57 kap 12 §)
  upprakningsranta ........... 0%        (SLOPAD, Prop. 2025/26:1)

statslanerantan .............. 2.55%     (Riksgälden, 30 nov 2025)

Plus: representation, traktamente, skattefria gåvor, reseavdrag, kostförmåner, SGI, SLP, pension.

What's inside /api/constants/kommunalskatt/2026

290 municipalities. Every entry has:

{
  "ale": {
    "kommunalskatt": 0.328,
    "begravningsavgift": 0.00292,
    "kyrkoavgift_snitt": 0.01
  }
}

kommunalskatt is the combined municipal + county rate. This is what Skatteverket publishes and what tax calculations use.

Verify API

Verification-as-a-service for Swedish tax calculations.

POST /api/verify — three modes

Mode 1 — VERIFY (send input + expected)

Your system calculated employer contributions on a 500 000 kr salary and got 157 100 kr. Is that right?

{
  "skill": "ag-avgifter",
  "input": {
    "gross_salary": 500000,
    "birth_year": 1990,
    "first_employee": false,
    "num_employees": 0
  },
  "expected": {
    "total_ag_avgift": 157100
  }
}

{
  "status": "PASS",
  "skill": "ag-avgifter",
  "actual": {
    "total_ag_avgift": 157100
  },
  "expected": {
    "total_ag_avgift": 157100
  },
  "diff": {},
  "sources": [
    { "name": "SFL 2 kap 26 §", ... }
  ],
  "disclaimer": "...",
  "engine_version": "2026.1",
  "timestamp": "2026-04-13T..."
}

If your number is wrong:

{
  "status": "FAIL",
  "diff": {
    "total_ag_avgift": {
      "expected": 160000,
      "actual": 157100,
      "delta": -2900
    }
  }
}

Mode 2 — CALCULATE (omit expected)

Don't have a number to verify? Send just the input. Response includes the full calculation, breakdown by component, legal sources, and disclaimer.

{
  "skill": "ag-avgifter",
  "input": {
    "gross_salary": 500000,
    "birth_year": 1990,
    "first_employee": false,
    "num_employees": 0
  }
}

Mode 3 — LIST (GET request)

GET /api/verify

Returns all available skills with their input schemas, descriptions, and assertion counts.

Available skills

Skills reference

Every skill is a pure function. Same input always produces the same output. No AI touches a number.

ag-avgifter

Calculates Swedish employer contributions for income year 2026.

Input

Output includes

total_ag_avgift — total employer contribution in SEK · ag_rate — effective rate (31.42% standard, 10.21% age-reduced or Växa) · total_lonekostnad — salary + AG combined · All 7 sub-components with individual amounts

Special cases

Legal source: SFL 2 kap 26–31 §

moms

Calculates Swedish VAT for income year 2026.

Input

Output includes

netto — amount excluding VAT · brutto — amount including VAT · moms_belopp — VAT amount · bas_konto — correct BAS account number (2610/2620/2630/2640)

Legal source: ML 7:1, ML 3 kap, ML 9d kap

bolagsskatt

Calculates Swedish corporate tax for income year 2026.

Input

Output includes

bolagsskatt — corporate tax in SEK · resultat_efter_skatt — profit after tax · periodiseringsfond_avdrag — actual fund deduction (capped at 25%) · schablonintakt — imputed income on existing funds (SLR × fund amounts) · aterford_fond — reversed fund (if any fund is 6+ years old)

Special cases

Legal source: IL 65 kap 10 §, IL 30 kap 5–7 §

k10

Calculates K10 shareholder allowance (gränsbelopp) for income year 2026.

Input

How the 2026 additive model works

gränsbelopp = grundbelopp
            + kapitalbaserat
            + lönebaserat
            + sparat utrymme

Where:
  grundbelopp    = 4 × 80 600 × ownership share = 322 400 kr (at 100%)
  kapitalbaserat = acquisition cost × (SLR + 9%) = cost × 11.55%
  lönebaserat    = 50% × (total salaries − 644 800 kr threshold)
  sparat         = prior year amount, carried forward at face value

Special cases

Legal source: IL 57 kap 11–16 §, Prop. 2025/26:1

Verification

Every number KAMMAREN returns is backed by verification.

Test suites

How golden cases work

We write expected values before writing the code. Each expected value is hand-calculated from Skatteverket's published tables (SKV 433, SFL, IL, ML). If the code produces a different number, the test fails.

Architecture

Any agent (Claude, GPT, local LLM, your own)
    │
    │ tool_call or HTTP POST
    ▼
┌───────────────────────────────────────┐
│  KAMMAREN                             │
│                                       │
│  skills/     → calculate()            │
│  constants/  → 2026.json (year-guard) │
│  verify/     → 304 assertions         │
│  vault/      → SHA-256 hash chain     │
└───────────┬───────────────────────────┘
            │
            ▼
  SkillOutput {
    result,      // exact numbers
    breakdown,   // component-by-component
    sources,     // law references with URLs
    disclaimer   // always present
  }

Principles

Limits and caveats

Links

License: AGPL-3.0-or-later. Run it, modify it, distribute it. If you distribute changes, publish your source. Commercial license available for closed-source use.

The formulas are public. The data is yours. The correctness is proven.