curl --request POST \
  --url https://sandbox.nmbr.co/services/payroll/form_types/{form_type}/validate \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "effective_date": "2026-01-01"
}
'

{
  "data": {
    "errors": {
      "line_2_infirm_children_caregiver_amount": [
        "The Infirm Children Caregiver Amount (Line 2) must be at least 0."
      ]
    }
  }
}