[Home](./index.md) > [@firebase/auth](./auth.md) > [ActionCodeURL](./auth.actioncodeurl.md) > [tenantId](./auth.actioncodeurl.tenantid.md) ## ActionCodeURL.tenantId property The tenant ID of the email action link. Null if the email action is from the parent project. Signature: ```typescript readonly tenantId: string | null; ```