For the fastest service, submit an application for an extension using our new My DOR services. Get help using My DOR for estate tax.What is the estate tax? How do I file the estate tax return? Texas does not have a state estate tax or inheritance tax. However, Texas residents still must adhere to federal estate tax guidelines. Generally, the estate tax return is due nine months after the date of death. A six month extension is available if requested prior to the due date. States deploying estate taxes include Massachusetts, New York, and Washington, among others. Understanding estate tax laws is crucial for estate planning.