diff --git a/schemas/2019-08-01/tenantDeploymentTemplate.json b/schemas/2019-08-01/tenantDeploymentTemplate.json
index c22a002de2..bf92aab2e3 100644
--- a/schemas/2019-08-01/tenantDeploymentTemplate.json
+++ b/schemas/2019-08-01/tenantDeploymentTemplate.json
@@ -610,6 +610,9 @@
                 {
                   "$ref": "https://schema.management.azure.com/schemas/2020-11-01-preview/Microsoft.Billing.json#/tenant_resourceDefinitions/promotions"
                 },
+                {
+                  "$ref": "https://schema.management.azure.com/schemas/2021-10-01/Microsoft.Billing.json#/tenant_resourceDefinitions/billingAccounts_billingSubscriptionAliases"
+                },
                 {
                   "$ref": "https://schema.management.azure.com/schemas/2019-04-01/Microsoft.Capacity.json#/tenant_resourceDefinitions/reservationOrders"
                 },
diff --git a/schemas/2021-10-01/Microsoft.Billing.json b/schemas/2021-10-01/Microsoft.Billing.json
new file mode 100644
index 0000000000..3814364b4c
--- /dev/null
+++ b/schemas/2021-10-01/Microsoft.Billing.json
@@ -0,0 +1,225 @@
+{
+  "id": "https://schema.management.azure.com/schemas/2021-10-01/Microsoft.Billing.json#",
+  "$schema": "http://json-schema.org/draft-04/schema#",
+  "title": "Microsoft.Billing",
+  "description": "Microsoft Billing Resource Types",
+  "resourceDefinitions": {},
+  "tenant_resourceDefinitions": {
+    "billingAccounts_billingSubscriptionAliases": {
+      "type": "object",
+      "properties": {
+        "apiVersion": {
+          "type": "string",
+          "enum": [
+            "2021-10-01"
+          ]
+        },
+        "name": {
+          "type": "string",
+          "description": "The ID that uniquely identifies a subscription alias."
+        },
+        "properties": {
+          "oneOf": [
+            {
+              "$ref": "#/definitions/BillingSubscriptionAliasProperties"
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "Billing subscription alias properties."
+        },
+        "type": {
+          "type": "string",
+          "enum": [
+            "Microsoft.Billing/billingAccounts/billingSubscriptionAliases"
+          ]
+        }
+      },
+      "required": [
+        "apiVersion",
+        "name",
+        "properties",
+        "type"
+      ],
+      "description": "Microsoft.Billing/billingAccounts/billingSubscriptionAliases"
+    }
+  },
+  "definitions": {
+    "Amount": {
+      "type": "object",
+      "properties": {},
+      "description": "The amount."
+    },
+    "BillingSubscriptionAliasProperties": {
+      "type": "object",
+      "properties": {
+        "autoRenew": {
+          "oneOf": [
+            {
+              "type": "string",
+              "enum": [
+                "Off",
+                "On"
+              ]
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "Indicates whether auto renewal is turned on or off for a subscription."
+        },
+        "beneficiaryTenantId": {
+          "type": "string",
+          "description": "The provisioning tenant of the subscription."
+        },
+        "billingFrequency": {
+          "type": "string",
+          "description": "The billing frequency of the subscription in the ISO8601 format. Example: P1M, P3M, P1Y"
+        },
+        "billingProfileId": {
+          "type": "string",
+          "description": "The ID of the billing profile to which the subscription is billed. This field is only applicable for Microsoft Customer Agreement billing accounts."
+        },
+        "consumptionCostCenter": {
+          "type": "string",
+          "description": "The cost center applied to the subscription. This field is only available for consumption subscriptions of Microsoft Customer Agreement Type billing accounts."
+        },
+        "customerId": {
+          "type": "string",
+          "description": "The ID of the customer for whom the subscription was created. The field is applicable only for Microsoft Partner Agreement billing accounts."
+        },
+        "displayName": {
+          "type": "string",
+          "description": "The name of the subscription."
+        },
+        "enrollmentAccountSubscriptionDetails": {
+          "oneOf": [
+            {
+              "$ref": "#/definitions/EnrollmentAccountSubscriptionDetails"
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "The billing properties that can be modified. This field is available only for the Enterprise Agreement billing accounts."
+        },
+        "invoiceSectionId": {
+          "type": "string",
+          "description": "The ID of the invoice section to which the subscription is billed. The field is applicable only for Microsoft Partner Agreement billing accounts."
+        },
+        "lastMonthCharges": {
+          "oneOf": [
+            {
+              "$ref": "#/definitions/Amount"
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "The amount."
+        },
+        "monthToDateCharges": {
+          "oneOf": [
+            {
+              "$ref": "#/definitions/Amount"
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "The amount."
+        },
+        "nextBillingCycleDetails": {
+          "oneOf": [
+            {
+              "$ref": "#/definitions/NextBillingCycleDetails"
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "The next billing cycle details of the subscription."
+        },
+        "productTypeId": {
+          "type": "string",
+          "description": "The ID of the product for which the subscription is purchased"
+        },
+        "quantity": {
+          "oneOf": [
+            {
+              "type": "integer"
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "The number of licenses purchased for the subscription"
+        },
+        "renewalTermDetails": {
+          "oneOf": [
+            {
+              "$ref": "#/definitions/RenewalTermDetails"
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "The term details of the subscription at renewal."
+        },
+        "reseller": {
+          "oneOf": [
+            {
+              "$ref": "#/definitions/Reseller"
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "Details of the reseller."
+        },
+        "skuId": {
+          "type": "string",
+          "description": "The SKU ID of the product for which the subscription is purchased. This field is only available for Microsoft Customer Agreement billing accounts."
+        },
+        "termDuration": {
+          "type": "string",
+          "description": "The duration for which you can use the subscription. Example P1Y and P1M"
+        }
+      },
+      "description": "Billing subscription alias properties."
+    },
+    "EnrollmentAccountSubscriptionDetails": {
+      "type": "object",
+      "properties": {},
+      "description": "The billing properties that can be modified. This field is available only for the Enterprise Agreement billing accounts."
+    },
+    "NextBillingCycleDetails": {
+      "type": "object",
+      "properties": {},
+      "description": "The next billing cycle details of the subscription."
+    },
+    "RenewalTermDetails": {
+      "type": "object",
+      "properties": {
+        "quantity": {
+          "oneOf": [
+            {
+              "type": "integer"
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "The number of licenses"
+        }
+      },
+      "description": "The term details of the subscription at renewal."
+    },
+    "Reseller": {
+      "type": "object",
+      "properties": {},
+      "description": "Details of the reseller."
+    }
+  }
+}
\ No newline at end of file