How do I authenticate?

Easiest via API key: create one in the self-service portal at api-portal.lohnica.de and send it in the X-API-Key header. Alternatively, the API supports OAuth2 with client credentials.

Which formats does the API use?

JSON over HTTPS. Months appear as YYYY-MM in the URL, amounts are decimal euro values, federal states are codes such as “by” or “nw”. Errors come back structured, with path and reason.

How up to date are the calculation values?

Health insurance supplementary rates are updated daily and income tax follows the official calculation schedules from 2022 onwards. Calculations for past months automatically use the values valid back then.

Where do I find the full reference?

In the Swagger UI at app.lohnica.de/api/v1/swagger-ui – generated from the same OpenAPI spec the service runs on. The spec can be downloaded as JSON, e.g. for Postman or code generators.

Contact

Developers

Your first API call in five minutes

Quickstart for the Lohnica Payroll API: authentication, first request, responses in milliseconds – plus OpenAPI spec, Swagger UI and MCP server.

Basics

What you need to know

Base URL: https://app.lohnica.de/api/v1
REST over HTTPS, requests and responses as JSON
Authentication via API key (X-API-Key header) or OAuth2
The payroll month is part of the URL, e.g. /gross-net-calc/2026-09
Calculations for past and future months use the rules valid at that time

https://app.lohnica.de/api/v1

Create an API key in the portal Open Swagger UI OpenAPI spec (JSON)

Quickstart

Your first call

A gross-to-net calculation for September 2026: €4,500 gross, tax class 1, Bavaria, Techniker Krankenkasse. The response arrives in milliseconds – abridged here, but the numbers are real.

Request

curl -X POST \
  https://app.lohnica.de/api/v1/gross-net-calc/2026-09 \
  -H "X-API-Key: <ihr-api-key>" \
  -H "Content-Type: application/json" \
  -d '{
    "monthly-gross-income": 4500,
    "income-tax-class": "1",
    "state": "by",
    "age": 35,
    "church-tax": false,
    "health-insurance-company-number": "15027365"
  }'

Response (abridged)

{
  "data": {
    "gross-income": 4500.0,
    "net-salary": 2874.31,
    "net-pay": 2874.31,
    "labor-cost": 5568.08,
    "employee": {
      "income-tax": 651.66,
      "health-insurance": 389.03,
      "nursing-care-insurance": 108.0,
      "pension-insurance": 418.5,
      "unemployment-insurance": 58.5,
      "insurance-total": 974.03
    },
    "employer": { "insurance-total": 1068.08 }
  }
}

Valid health insurance company numbers come from GET /health-insurances/ – updated daily including supplementary rates.

Reference

Four calculation types, one call pattern

Company pensions and company cars are included in all four calculation types.

Gross → net

POST /gross-net-calc/

From gross salary to net pay, deductions and employer costs – the classic.

Net → gross

POST /net-gross-calc/

From a target net salary back to the required gross – e.g. for salary negotiations.

Labour cost → net

POST /cost-net-calc/

From budget to salary: which gross and net fit into €X of total employer cost?

Trial payroll run

POST /simulate/

The complete payroll run with full master data and a wide range of wage types – benefits such as recreation allowance, Deutschlandticket or meal vouchers including flat-rate taxation and contribution pass-through, plus PDF export.

AI assistants

Prefer no code at all?

All calculation types are also available as MCP tools: mcp.lohnica.de connects Claude, Cursor and friends directly to the Lohnica API – no local installation.

Explore the AI integration

FAQ

Frequently asked questions

The quickest impression is the salary calculator on this website – it runs on the same API. For your own tests, register in the API portal and create your own API key – no waiting, usage overview included.

Contact

Questions about your integration?

You create your API key yourself in the API portal. For everything else – Payroll API, volumes, consulting – just get in touch.

info@lohnica.de