At the cost of a slightly more complex schema, the JSON representation can be made much more readable:

    {
      "path": "/tentativeTaxNetNonRefundableCredits",
      "description": "Total tentative tax after applying non-refundable credits, but before applying refundable credits.",
      "maxOf": [
        {
          "const": {
            "value": 0,
            "currency": "Dollar"
          }
        },
        {
          "subtract": {
            "from": "/totalTentativeTax",
            "amount": "/totalNonRefundableCredits"
          }
        }
      ]
    }