They say that nothing in life is free, but that isn't true. You can get a nine-digit federal tax ID number from the IRS absolutely free of charge. And it's easy. In fact, it is perhaps easier to get a tax ID number than it is to figure out whether your business needs one. You apply for the federal tax ID number with a one-page form, and you can get that form to the IRS in any a number of convenient ways.
TL;DR (Too Long; Didn't Read)
You can get a federal tax ID number from the IRS by submitting an SS-4 application online, by fax or in the mail, or you can apply by telephone.
How Do You Get a Federal Tax ID Number?
If you are starting a business, hiring employees or changing the character of a business you already have, you may need a federal tax ID number. This is also called an employer identification number or EIN.
The IRS makes it easy for you to get an EIN using a SS-4 form. This is a one-page form asking general questions about business, like its name, the type of business, the work it does and so on. You'll also have to identify yourself as the responsible person and include your SSN. The application and the EIN are free from the IRS, so don't fall for any internet scam ads charging to get you one. Just fill in the SS-4 and decide how you want to send it.
If you need a federal tax ID number fast, you'll do best to apply for it online. You can do this if the business is located in the United States or its territories and the individual responsible for it has a Social Security number. If you can wait five days, fax in the SS-4 form and get an EIN by fax in return. If you prefer snail-mail, this is also possible, but you may not get your federal tax ID number for a month. International applicants also have the option of phoning in the information needed and getting an EIN immediately.
What is an SOS ID Number?
An SOS number is one name for a state tax ID. These operate sort of like a federal tax ID number, but are used for state taxes. The SOS stands for Secretary of State. You apply for an SOS number with the state taxing authority.
How to Get a Federal Tax ID Number for an Estate
When a person dies, the assets heowned in life become the property of his estate. If you are the executor of the estate, you may need to file an estate income tax return (Form 1041) if the assets generate income to the estate.
You cannot file this estate income tax return using the SSN of the person who died. He and his estate are separate taxable entities. Instead, to file Form 1041, you must obtain a tax ID number (EIN) for the estate. Apply for an EIN for an estate with the SS-4 form online, by fax or by mail. In the question about the form of the business, mark "estate" and insert the SSN of the decedent.