curl --request POST \
  --url https://api.become1.de/api/v2/flex/tax-rule-templates \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "name": "<string>",
  "rules": [
    {
      "budgets": [
        {
          "budget": {
            "value": 123
          }
        }
      ],
      "maxDaysPerMonth": 123,
      "isOnlyPublicTransportAllowed": true
    }
  ],
  "companyIds": [
    "<string>"
  ]
}
'

{
  "id": "<string>",
  "companyIds": [
    "<string>"
  ],
  "name": "<string>",
  "rules": [
    "<array>"
  ],
  "taxAffiliations": []
}