While you are still living, your revocable trust has no need for a separate tax identification number. They are actually associated with you until death.
The answer to this question in one word is “No.” You don't need a separate tax ID number for a revocable trust while the owner is alive. The social security number is enough.
But I suppose you are not here for a 'one word' answer. So, let's dive a little deeper into the topic.
A revocable trust means a trust that can be changed or eliminated. A trustor (the owner) can add and remove assets as they please or revoke the entire trust if they want. A trustee manages the property or assets. Distributing the wealth to the beneficiaries is another duty of the trustee.
Revocable trusts are commonly known as "living trusts." They are a useful estate-planning strategy for reducing the expenses and difficulties of probate, protecting privacy, and setting up your assets for convenience of transfer after your demise.
Allegedly, some banks push you to get a separate tax ID number for a revocable trust. If they trap you into getting a separate employer identification number (EIN) or a new EIN, you'll have to fill out IRS form SS-4. Then come tax time you'll receive a letter from the Internal Revenue Service (IRS) asking why you didn't file the trust tax return alongside your own tax return. And you'll have to pay your accountant to send a letter saying it doesn't need to be filed.
So I'll say it again, you don't need a separate tax identification number for a revocable trust during the life of the owner/creator.
Your revocable trust isn't a separate legal entity. It's under your control, a separate legal entity with a tax ID number. So, the trust isn't separate from its creator. Moreover, it's not separate from the creator's spouse.
Separate tax ID numbers are needed for legal entities, and since the trust isn't independent and the creator controls it, it doesn't need a tax ID number or as some think its own social security number. The grantor’s social security number is just fine.
However, when the owner (trustor) dies, the trust becomes irrevocable. After the death of the grantor, no one can change its terms or terminate the trust. It becomes a legal entity and needs a separate trust tax ID number, will have its own separate income tax return, and for federal income tax purposes will be taxed as such.
A revocable trust can be changed or revoked by the original owner at any time. Unlike an irrevocable trust, which cannot be changed once it is created, or a charitable remainder trust, which must be used for charitable purposes, a revocable trust gives the owner complete control over the assets in the trust.
This means that the revocable trusts do not have a separate legal existence from the owner. Assets in a revocable trust are not separated from the owner's personal assets—the owner keeps control over the assets in the trust during his lifetime.
They can change the terms of the type of trust, add or remove assets, change the name of the trust, or even revoke the trust entirely if they so choose. The only exception is if the trust has already been used to purchase property, the property would need to be sold to get removed from the trust.
You may choose any of the different kinds of estate plans. Each plan has different purposes, benefits, and drawbacks. A revocable trust is good to set up to avoid the probate procedure and access to the public. But it doesn't protect all your assets or provide any tax advantages. Moreover, a revocable trust doesn't need its own EIN because it's not separate from the creator. So, the social security number of the owner is enough.
This is not legal advice from a law firm, so as always the general rule is to do your own research.