diff --git a/azurerm/internal/acceptance/testcase.go b/azurerm/internal/acceptance/testcase.go
index 3f62e938c372..ef98b4c446df 100644
--- a/azurerm/internal/acceptance/testcase.go
+++ b/azurerm/internal/acceptance/testcase.go
@@ -91,6 +91,10 @@ func (td TestData) runAcceptanceTest(t *testing.T, testCase resource.TestCase) {
 			azurerm := provider.TestAzureProvider()
 			return azurerm, nil
 		},
+		"azurerm-alt": func() (terraform.ResourceProvider, error) {
+			azurerm := provider.TestAzureProvider()
+			return azurerm, nil
+		},
 	}
 
 	resource.ParallelTest(t, testCase)
diff --git a/azurerm/internal/services/keyvault/client/client.go b/azurerm/internal/services/keyvault/client/client.go
index 1f01511dead5..28a5a0b3e0d0 100644
--- a/azurerm/internal/services/keyvault/client/client.go
+++ b/azurerm/internal/services/keyvault/client/client.go
@@ -10,6 +10,7 @@ type Client struct {
 	ManagedHsmClient *keyvault.ManagedHsmsClient
 	ManagementClient *keyvaultmgmt.BaseClient
 	VaultsClient     *keyvault.VaultsClient
+	options          *common.ClientOptions
 }
 
 func NewClient(o *common.ClientOptions) *Client {
@@ -26,5 +27,12 @@ func NewClient(o *common.ClientOptions) *Client {
 		ManagedHsmClient: &managedHsmClient,
 		ManagementClient: &managementClient,
 		VaultsClient:     &vaultsClient,
+		options:          o,
 	}
 }
+
+func (client Client) KeyVaultClientForSubscription(subscriptionId string) *keyvault.VaultsClient {
+	vaultsClient := keyvault.NewVaultsClientWithBaseURI(client.options.ResourceManagerEndpoint, subscriptionId)
+	client.options.ConfigureClient(&vaultsClient.Client, client.options.ResourceManagerAuthorizer)
+	return &vaultsClient
+}
diff --git a/azurerm/internal/services/keyvault/client/helpers.go b/azurerm/internal/services/keyvault/client/helpers.go
index c56ab4940038..cd16de5c6702 100644
--- a/azurerm/internal/services/keyvault/client/helpers.go
+++ b/azurerm/internal/services/keyvault/client/helpers.go
@@ -43,6 +43,10 @@ func (c *Client) BaseUriForKeyVault(ctx context.Context, keyVaultId parse.VaultI
 	lock[cacheKey].Lock()
 	defer lock[cacheKey].Unlock()
 
+	if keyVaultId.SubscriptionId != c.VaultsClient.SubscriptionID {
+		c.VaultsClient = c.KeyVaultClientForSubscription(keyVaultId.SubscriptionId)
+	}
+
 	resp, err := c.VaultsClient.Get(ctx, keyVaultId.ResourceGroup, keyVaultId.Name)
 	if err != nil {
 		if utils.ResponseWasNotFound(resp.Response) {
diff --git a/azurerm/internal/services/storage/storage_account_customer_managed_key_resource.go b/azurerm/internal/services/storage/storage_account_customer_managed_key_resource.go
index c79c06ce1fc6..01e8a76377be 100644
--- a/azurerm/internal/services/storage/storage_account_customer_managed_key_resource.go
+++ b/azurerm/internal/services/storage/storage_account_customer_managed_key_resource.go
@@ -84,7 +84,7 @@ func resourceStorageAccountCustomerManagedKeyCreateUpdate(d *pluginsdk.ResourceD
 
 	storageAccount, err := storageClient.GetProperties(ctx, storageAccountID.ResourceGroup, storageAccountID.Name, "")
 	if err != nil {
-		return fmt.Errorf("Error retrieving Storage Account %q (Resource Group %q): %+v", storageAccountID.Name, storageAccountID.ResourceGroup, err)
+		return fmt.Errorf("retrieving Storage Account %q (Resource Group %q): %+v", storageAccountID.Name, storageAccountID.ResourceGroup, err)
 	}
 	if storageAccount.AccountProperties == nil {
 		return fmt.Errorf("Error retrieving Storage Account %q (Resource Group %q): `properties` was nil", storageAccountID.Name, storageAccountID.ResourceGroup)
@@ -94,7 +94,7 @@ func resourceStorageAccountCustomerManagedKeyCreateUpdate(d *pluginsdk.ResourceD
 	resourceID := storageAccountIDRaw
 
 	if d.IsNewResource() {
-		// whilst this looks superflurious given encryption is enabled by default, due to the way
+		// whilst this looks superfluous given encryption is enabled by default, due to the way
 		// the Azure API works this technically can be nil
 		if storageAccount.AccountProperties.Encryption != nil {
 			if storageAccount.AccountProperties.Encryption.KeySource == storage.KeySourceMicrosoftKeyvault {
@@ -108,6 +108,11 @@ func resourceStorageAccountCustomerManagedKeyCreateUpdate(d *pluginsdk.ResourceD
 		return err
 	}
 
+	// If the Keyvault is in another subscription we need to update the client
+	if keyVaultID.SubscriptionId != vaultsClient.SubscriptionID {
+		vaultsClient = meta.(*clients.Client).KeyVault.KeyVaultClientForSubscription(keyVaultID.SubscriptionId)
+	}
+
 	keyVault, err := vaultsClient.Get(ctx, keyVaultID.ResourceGroup, keyVaultID.Name)
 	if err != nil {
 		return fmt.Errorf("Error retrieving Key Vault %q (Resource Group %q): %+v", keyVaultID.Name, keyVaultID.ResourceGroup, err)
@@ -129,7 +134,7 @@ func resourceStorageAccountCustomerManagedKeyCreateUpdate(d *pluginsdk.ResourceD
 
 	keyVaultBaseURL, err := keyVaultsClient.BaseUriForKeyVault(ctx, *keyVaultID)
 	if err != nil {
-		return fmt.Errorf("Error looking up Key Vault URI from Key Vault %q (Resource Group %q): %+v", keyVaultID.Name, keyVaultID.ResourceGroup, err)
+		return fmt.Errorf("looking up Key Vault URI from Key Vault %q (Resource Group %q) (Subscription %q): %+v", keyVaultID.Name, keyVaultID.ResourceGroup, keyVaultsClient.VaultsClient.SubscriptionID, err)
 	}
 
 	keyName := d.Get("key_name").(string)
diff --git a/azurerm/internal/services/storage/storage_account_customer_managed_key_resource_test.go b/azurerm/internal/services/storage/storage_account_customer_managed_key_resource_test.go
index d401ef76d5de..165e643abe2c 100644
--- a/azurerm/internal/services/storage/storage_account_customer_managed_key_resource_test.go
+++ b/azurerm/internal/services/storage/storage_account_customer_managed_key_resource_test.go
@@ -99,6 +99,20 @@ func TestAccStorageAccountCustomerManagedKey_testKeyVersion(t *testing.T) {
 	})
 }
 
+func TestAccAzureRMStorageAccountCustomerManagedKey_remoteKeyVault(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_storage_account_customer_managed_key", "test")
+	r := StorageAccountCustomerManagedKeyResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.remoteKeyVault(data),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+	})
+}
+
 func (r StorageAccountCustomerManagedKeyResource) accountHasDefaultSettings(ctx context.Context, client *clients.Client, state *pluginsdk.InstanceState) error {
 	accountId, err := storageParse.StorageAccountID(state.Attributes["id"])
 	if err != nil {
@@ -234,6 +248,115 @@ resource "azurerm_storage_account_customer_managed_key" "test" {
 `, template)
 }
 
+// (@jackofallops) - This test spans 2 subscriptions to check that it's possible to use a CMK stored in a vault in a non-local subscription. This is temporarily making use of an extra providerfactory which will need to be removed after the move to plugin-sdk-go
+// TODO - review this config when plugin-sdk-go is implemented in the provider / test framework.
+func (r StorageAccountCustomerManagedKeyResource) remoteKeyVault(data acceptance.TestData) string {
+	clientData := data.Client()
+	return fmt.Sprintf(`
+provider "azurerm" {
+  features {}
+}
+
+provider "azurerm-alt" {
+  subscription_id = "%s"
+  tenant_id       = "%s"
+  features {
+    key_vault {
+      purge_soft_delete_on_destroy = false
+    }
+  }
+}
+
+data "azurerm_client_config" "current" {}
+
+resource "azurerm_resource_group" "remotetest" {
+  provider = azurerm-alt
+
+  name     = "acctestRG-alt-%d"
+  location = "%s"
+}
+
+resource "azurerm_key_vault" "remotetest" {
+  provider = azurerm-alt
+
+  name                     = "acctestkv%s"
+  location                 = azurerm_resource_group.remotetest.location
+  resource_group_name      = azurerm_resource_group.remotetest.name
+  tenant_id                = "%s"
+  sku_name                 = "standard"
+  purge_protection_enabled = true
+}
+
+resource "azurerm_key_vault_access_policy" "storage" {
+  provider = azurerm-alt
+
+  key_vault_id = azurerm_key_vault.remotetest.id
+  tenant_id    = data.azurerm_client_config.current.tenant_id
+  object_id    = azurerm_storage_account.test.identity.0.principal_id
+
+  key_permissions    = ["get", "create", "list", "restore", "recover", "unwrapkey", "wrapkey", "purge", "encrypt", "decrypt", "sign", "verify"]
+  secret_permissions = ["get"]
+}
+
+resource "azurerm_key_vault_access_policy" "client" {
+  provider = azurerm-alt
+
+  key_vault_id = azurerm_key_vault.remotetest.id
+  tenant_id    = data.azurerm_client_config.current.tenant_id
+  object_id    = data.azurerm_client_config.current.object_id
+
+  key_permissions    = ["get", "create", "delete", "list", "restore", "recover", "unwrapkey", "wrapkey", "purge", "encrypt", "decrypt", "sign", "verify"]
+  secret_permissions = ["get"]
+}
+
+resource "azurerm_key_vault_key" "remote" {
+  provider = azurerm-alt
+
+  name         = "remote"
+  key_vault_id = azurerm_key_vault.remotetest.id
+  key_type     = "RSA"
+  key_size     = 2048
+  key_opts     = ["decrypt", "encrypt", "sign", "unwrapKey", "verify", "wrapKey"]
+
+  depends_on = [
+    azurerm_key_vault_access_policy.client,
+    azurerm_key_vault_access_policy.storage,
+  ]
+}
+
+resource "azurerm_resource_group" "test" {
+  provider = azurerm
+
+  name     = "acctestRG-%d"
+  location = "%s"
+}
+
+resource "azurerm_storage_account" "test" {
+  provider = azurerm
+
+  name                     = "acctestsa%s"
+  resource_group_name      = azurerm_resource_group.test.name
+  location                 = azurerm_resource_group.test.location
+  account_tier             = "Standard"
+  account_replication_type = "LRS"
+
+  identity {
+    type = "SystemAssigned"
+  }
+}
+
+resource "azurerm_storage_account_customer_managed_key" "test" {
+  provider = azurerm
+
+  storage_account_id = azurerm_storage_account.test.id
+  key_vault_id       = azurerm_key_vault.remotetest.id
+  key_name           = azurerm_key_vault_key.remote.name
+  key_version        = azurerm_key_vault_key.remote.version
+}
+
+`, clientData.SubscriptionIDAlt, clientData.TenantID, data.RandomInteger, data.Locations.Primary, data.RandomString, clientData.TenantID, data.RandomInteger, data.Locations.Primary, data.RandomString)
+}
+
 func (r StorageAccountCustomerManagedKeyResource) template(data acceptance.TestData) string {
 	return fmt.Sprintf(`
 provider "azurerm" {