Azure – What am I missing editing Policy

In your policy, Tag names such as tagName and tagName1, must be separately defined within the parameters object. The concatenated tag names should be used in the field condition of the policy rule to check for their existence.

Here is the updated policy.

    {
      "mode": "All",
      "policyRule": {
        "if": {
          "allOf": [
            {
              "field": "type",
              "equals": "Microsoft.Resources/subscriptions/resourceGroups"
            },
            {
              "field": "[concat('tags[', parameters('tagName'), ',', parameters('tagName1'), ']')]",
              "exists": "false"
            }
          ]
        },
        "then": {
          "effect": "deny"
        }
      },
      "parameters": {
        "tagName": {
          "type": "String",
          "metadata": {
            "displayName": "Tag Name",
            "description": "Name of the tag, such as 'pailot'"
          }
        },
        "tagName1": {
          "type": "String",
          "metadata": {
            "displayName": "Project",
            "description": "Name of the tag, such as 'environment'"
          }
        }
      }
    }

Output:

The policy is denying the resource group with different tag names.