Sample Azure Policy rule to match a specific tag pattern

tag-match-policy-rule.json

"policyRule": {
  "if": {
    "field": "[[concat('tags[', parameters('tagName'), ']')]", // For example, 'application' as the tag name
    "notMatch": "??##-??????????" // To match pattern like 'AC01-FinanceApp'
  },
  "then": {
    // Some policy effect...
  }
}